Check for Debug impls for all types

This was not compile-tested on all platforms, but instead all `pub enum`
types had a `Debug` impl derived for them.
diff --git a/src/cloudabi/mod.rs b/src/cloudabi/mod.rs
index df11de0..520ed8d 100644
--- a/src/cloudabi/mod.rs
+++ b/src/cloudabi/mod.rs
@@ -122,7 +122,9 @@
 pub const SOCK_DGRAM: ::c_int = 128;
 pub const SOCK_STREAM: ::c_int = 130;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum FILE {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos_t {} // TODO: fill this out with a struct
 
 extern {
diff --git a/src/fuchsia/mod.rs b/src/fuchsia/mod.rs
index e785fab..351ec7e 100644
--- a/src/fuchsia/mod.rs
+++ b/src/fuchsia/mod.rs
@@ -100,9 +100,13 @@
 
 // FIXME: why are these uninhabited types? that seems... wrong?
 // Presumably these should be `()` or an `extern type` (when that stabilizes).
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum DIR {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum locale_t {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos64_t {} // TODO: fill this out with a struct
 
 // PUB_STRUCT
@@ -3042,7 +3046,9 @@
 #[link(name = "fdio")]
 extern {}
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum FILE {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos_t {} // TODO: fill this out with a struct
 
 extern {
diff --git a/src/lib.rs b/src/lib.rs
index 03e7804..86ab9b1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -156,6 +156,8 @@
 #![cfg_attr(feature = "rustc-dep-of-std", no_core)]
 #![cfg_attr(feature = "rustc-dep-of-std", allow(warnings))]
 #![cfg_attr(not(any(feature = "use_std", feature = "rustc-dep-of-std")), no_std)]
+// Enable lints
+#![cfg_attr(feature = "extra_traits", deny(missing_debug_implementations))]
 
 #[cfg(all(not(cross_platform_docs), feature = "use_std"))]
 extern crate std as core;
diff --git a/src/redox/mod.rs b/src/redox/mod.rs
index 8dabd90..cfe7fd6 100644
--- a/src/redox/mod.rs
+++ b/src/redox/mod.rs
@@ -219,7 +219,9 @@
 pub const SIGPWR:    ::c_int = 30;
 pub const SIGSYS:    ::c_int = 31;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum FILE {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos_t {} // TODO: fill this out with a struct
 
 // intentionally not public, only used for fd_set
diff --git a/src/unix/bsd/apple/mod.rs b/src/unix/bsd/apple/mod.rs
index 0899591..bb48d22 100644
--- a/src/unix/bsd/apple/mod.rs
+++ b/src/unix/bsd/apple/mod.rs
@@ -34,6 +34,7 @@
 pub type key_t = ::c_int;
 pub type shmatt_t = ::c_ushort;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/unix/bsd/freebsdlike/dragonfly/mod.rs b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
index 992d008..75afeb2 100644
--- a/src/unix/bsd/freebsdlike/dragonfly/mod.rs
+++ b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
@@ -17,6 +17,7 @@
 
 pub type sem_t = *mut sem;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum sem {}
 
 s! {
diff --git a/src/unix/bsd/freebsdlike/mod.rs b/src/unix/bsd/freebsdlike/mod.rs
index 22c11b3..a402269 100644
--- a/src/unix/bsd/freebsdlike/mod.rs
+++ b/src/unix/bsd/freebsdlike/mod.rs
@@ -16,6 +16,7 @@
 pub type nl_item = ::c_int;
 pub type id_t = i64;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/unix/bsd/netbsdlike/mod.rs b/src/unix/bsd/netbsdlike/mod.rs
index 291c081..dfe2051 100644
--- a/src/unix/bsd/netbsdlike/mod.rs
+++ b/src/unix/bsd/netbsdlike/mod.rs
@@ -13,7 +13,9 @@
 pub type id_t = ::uint32_t;
 pub type sem_t = *mut sem;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum sem {}
 
 s! {
diff --git a/src/unix/haiku/mod.rs b/src/unix/haiku/mod.rs
index 2aa5d13..a7fdffd 100644
--- a/src/unix/haiku/mod.rs
+++ b/src/unix/haiku/mod.rs
@@ -31,6 +31,7 @@
 pub type id_t = i32;
 pub type idtype_t = ::c_uint;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index 88e13c5..bcd16f8 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -41,7 +41,9 @@
 pub type sighandler_t = ::size_t;
 pub type cc_t = ::c_uchar;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum DIR {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum locale_t {}
 
 s! {
@@ -365,7 +367,9 @@
     }
 }
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum FILE {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos_t {} // TODO: fill this out with a struct
 
 extern {
diff --git a/src/unix/notbsd/android/mod.rs b/src/unix/notbsd/android/mod.rs
index de4ff59..0e2eebf 100644
--- a/src/unix/notbsd/android/mod.rs
+++ b/src/unix/notbsd/android/mod.rs
@@ -264,7 +264,7 @@
             .field("d_off", &self.d_off)
             .field("d_reclen", &self.d_reclen)
             .field("d_type", &self.d_type)
-            .field("d_name", &self.d_name)
+            // FIXME: .field("d_name", &self.d_name)
             .finish()
     }
 }
@@ -302,7 +302,7 @@
             .field("d_off", &self.d_off)
             .field("d_reclen", &self.d_reclen)
             .field("d_type", &self.d_type)
-            .field("d_name", &self.d_name)
+            // FIXME: .field("d_name", &self.d_name)
             .finish()
     }
 }
@@ -374,7 +374,7 @@
         f.debug_struct("lastlog")
             .field("ll_time", &self.ll_time)
             .field("ll_line", &self.ll_line)
-            .field("ll_host", &self.ll_host)
+            // FIXME: .field("ll_host", &self.ll_host)
             .finish()
     }
 }
@@ -425,7 +425,7 @@
             .field("ut_line", &self.ut_line)
             .field("ut_id", &self.ut_id)
             .field("ut_user", &self.ut_user)
-            .field("ut_host", &self.ut_host)
+            // FIXME: .field("ut_host", &self.ut_host)
             .field("ut_exit", &self.ut_exit)
             .field("ut_session", &self.ut_session)
             .field("ut_tv", &self.ut_tv)
diff --git a/src/unix/notbsd/emscripten.rs b/src/unix/notbsd/emscripten.rs
index 28791d8..069631c 100644
--- a/src/unix/notbsd/emscripten.rs
+++ b/src/unix/notbsd/emscripten.rs
@@ -35,6 +35,7 @@
 pub type c_ulong = u32;
 pub type nlink_t = u32;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos64_t {} // TODO: fill this out with a struct
 
 s! {
diff --git a/src/unix/notbsd/linux/mod.rs b/src/unix/notbsd/linux/mod.rs
index 31fc379..3150887 100644
--- a/src/unix/notbsd/linux/mod.rs
+++ b/src/unix/notbsd/linux/mod.rs
@@ -38,6 +38,7 @@
 pub type Elf32_Section = u16;
 pub type Elf64_Section = u16;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos64_t {} // TODO: fill this out with a struct
 
 s! {
diff --git a/src/unix/notbsd/mod.rs b/src/unix/notbsd/mod.rs
index 4b06e6e..7913508 100644
--- a/src/unix/notbsd/mod.rs
+++ b/src/unix/notbsd/mod.rs
@@ -8,6 +8,7 @@
 pub type key_t = ::c_int;
 pub type id_t = ::c_uint;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/unix/solaris/mod.rs b/src/unix/solaris/mod.rs
index c991e62..c10f4c1 100644
--- a/src/unix/solaris/mod.rs
+++ b/src/unix/solaris/mod.rs
@@ -36,6 +36,7 @@
 pub type id_t = ::c_int;
 pub type idtype_t = ::c_uint;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/unix/uclibc/mod.rs b/src/unix/uclibc/mod.rs
index c04c22a..e062004 100644
--- a/src/unix/uclibc/mod.rs
+++ b/src/unix/uclibc/mod.rs
@@ -24,8 +24,10 @@
 pub type nl_item = ::c_int;
 pub type idtype_t = ::c_uint;
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos64_t {} // TODO: fill this out with a struct
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 
 s! {
diff --git a/src/windows/mod.rs b/src/windows/mod.rs
index 4bea459..9deaf9b 100644
--- a/src/windows/mod.rs
+++ b/src/windows/mod.rs
@@ -47,6 +47,7 @@
 pub type off_t = i32;
 pub type dev_t = u32;
 pub type ino_t = u16;
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
 pub type time64_t = i64;
 
@@ -201,7 +202,9 @@
 #[link(name = "libcmt", cfg(target_feature = "crt-static"))]
 extern {}
 
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum FILE {}
+#[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos_t {} // TODO: fill this out with a struct
 
 extern {
@@ -446,4 +449,4 @@
     } else {
         // Unknown target_env
     }
-}
\ No newline at end of file
+}