Fix foolish #[cfg] mistake

Author: asomers

libc-test/test/cmsg.rs

@@ -2,16 +2,17 @@
 //! various inputs.
 
 extern crate libc;
-use libc::{c_uchar, c_uint, c_void, cmsghdr, msghdr};
-use std::{mem, ptr};
 
 // Run these tests on all Unixen, but skip them on platforms that fail due to
 // suspected QEMU bugs.  Sparc64 gets SIGILL and s390x hangs, both before
 // executing any test functions.
 #[cfg(all(unix,
           not(target_arch = "sparc64"),
           not(target_arch = "s390x")))]
-{
+mod cmsg {
+
+use libc::{c_uchar, c_uint, c_void, cmsghdr, msghdr};
+use std::{mem, ptr};
 
 extern {
     pub fn cmsg_firsthdr(msgh: *const msghdr) -> *mut cmsghdr;