haiku: updated with recommends for signal

Author: Al Hoang

src/sys/signal.rs

@@ -90,6 +90,7 @@ libc_enum!{
         SIGWINCH,
         /// Input/output possible signal
         #[cfg(not(target_os = "haiku"))]
+        #[cfg_attr(docsrs, doc(cfg(all())))]
         SIGIO,
         #[cfg(any(target_os = "android", target_os = "emscripten",
                   target_os = "fuchsia", target_os = "linux"))]
@@ -106,10 +107,9 @@ libc_enum!{
         SIGEMT,
         #[cfg(not(any(target_os = "android", target_os = "emscripten",
                       target_os = "fuchsia", target_os = "linux",
-                      target_os = "redox")))]
+                      target_os = "redox", target_os = "haiku")))]
         #[cfg_attr(docsrs, doc(cfg(all())))]
         /// Information request
-        #[cfg(not(target_os = "haiku"))]
         SIGINFO,
     }
     impl TryFrom<i32>