signal: Also cfg gate the entire unix::bsd module

src/unix.rs

@@ -34,6 +34,13 @@ pub use self::libc::{SIGUSR1, SIGUSR2, SIGINT, SIGTERM};
 pub use self::libc::{SIGALRM, SIGHUP, SIGPIPE, SIGQUIT, SIGTRAP};
 
 /// BSD-specific definitions
+#[cfg(any(
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+))]
 mod bsd {
     #[cfg(any(target_os = "dragonfly", target_os = "freebsd",
               target_os = "macos", target_os = "netbsd",