make some symbols linux-specific
diff --git a/src/unix/notbsd/linux/mod.rs b/src/unix/notbsd/linux/mod.rs
index 7cc059a..a6ac3b5 100644
--- a/src/unix/notbsd/linux/mod.rs
+++ b/src/unix/notbsd/linux/mod.rs
@@ -1407,6 +1407,9 @@
 pub const SIOCGIFMAP: ::c_ulong = 0x00008970;
 pub const SIOCSIFMAP: ::c_ulong = 0x00008971;
 
+pub const IPTOS_TOS_MASK: u8 = 0x1E;
+pub const IPTOS_PREC_MASK: u8 = 0xE0;
+
 f! {
     pub fn CPU_ZERO(cpuset: &mut cpu_set_t) -> () {
         for slot in cpuset.bits.iter_mut() {
@@ -1462,6 +1465,14 @@
         dev |= (minor & 0xffffff00) << 12;
         dev
     }
+
+    pub fn IPTOS_TOS(tos: u8) -> u8 {
+        tos & IPTOS_TOS_MASK
+    }
+
+    pub fn IPTOS_PREC(tos: u8) -> u8 {
+        tos & IPTOS_PREC_MASK
+    }
 }
 
 extern {
diff --git a/src/unix/notbsd/mod.rs b/src/unix/notbsd/mod.rs
index 31a520d..2a6d616 100644
--- a/src/unix/notbsd/mod.rs
+++ b/src/unix/notbsd/mod.rs
@@ -824,14 +824,11 @@
 pub const POLLRDNORM: ::c_short = 0x040;
 pub const POLLRDBAND: ::c_short = 0x080;
 
-pub const IPTOS_TOS_MASK: u8 = 0x1E;
 pub const IPTOS_LOWDELAY: u8 = 0x10;
 pub const IPTOS_THROUGHPUT: u8 = 0x08;
 pub const IPTOS_RELIABILITY: u8 = 0x04;
 pub const IPTOS_MINCOST: u8 = 0x02;
 
-pub const IPTOS_PREC_MASK: u8 = 0xE0;
-
 pub const IPTOS_PREC_NETCONTROL: u8 = 0xe0;
 pub const IPTOS_PREC_INTERNETCONTROL: u8 = 0xc0;
 pub const IPTOS_PREC_CRITIC_ECP: u8 = 0xa0;
@@ -936,14 +933,6 @@
         (cmd << 8) | (type_ & 0x00ff)
     }
 
-    pub fn IPTOS_TOS(tos: u8) -> u8 {
-        tos & IPTOS_TOS_MASK
-    }
-
-    pub fn IPTOS_PREC(tos: u8) -> u8 {
-        tos & IPTOS_PREC_MASK
-    }
-
     pub fn IPOPT_COPIED(o: u8) -> u8 {
         o & IPOPT_COPY
     }