Move verbase-trace to a RUSTFLAGS env flag
diff --git a/src/cursor.rs b/src/cursor.rs
index cf22996..1ee82b2 100644
--- a/src/cursor.rs
+++ b/src/cursor.rs
@@ -13,7 +13,7 @@
 use std::ptr;
 use std::marker::PhantomData;
 
-#[cfg(all(feature = "verbose-trace", not(feature = "all-features")))]
+#[cfg(synom_verbose_trace)]
 use std::fmt::{self, Debug};
 
 /// Internal type which is used instead of `TokenTree` to represent a single
@@ -310,7 +310,7 @@
 
 // We do a custom implementation for `Debug` as the default implementation is
 // pretty useless.
-#[cfg(all(feature = "verbose-trace", not(feature = "all-features")))]
+#[cfg(synom_verbose_trace)]
 impl<'a> Debug for Cursor<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // Print what the cursor is currently looking at.
diff --git a/src/parsers.rs b/src/parsers.rs
index ae7d00f..38c7ab0 100644
--- a/src/parsers.rs
+++ b/src/parsers.rs
@@ -81,7 +81,7 @@
     };
 }
 
-#[cfg(all(feature = "verbose-trace", not(feature = "all-features")))]
+#[cfg(synom_verbose_trace)]
 #[macro_export]
 macro_rules! call {
     ($i:expr, $fun:expr $(, $args:expr)*) => {{
@@ -128,7 +128,7 @@
 /// #
 /// # fn main() {}
 /// ```
-#[cfg(any(not(feature = "verbose-trace"), feature = "all-features"))]
+#[cfg(not(synom_verbose_trace))]
 #[macro_export]
 macro_rules! call {
     ($i:expr, $fun:expr $(, $args:expr)*) => {