Flag the dynamic_lib tests as ignored

The library isn't thread-safe, cc #9137

Author: alexcrichton

src/libstd/unstable/dynamic_lib.rs

@@ -90,7 +90,8 @@ mod test {
     use libc;
 
     #[test]
-    #[ignore(cfg(windows))] // FIXME #8818
+    // #[ignore(cfg(windows))] // FIXME #8818
+    #[ignore] // FIXME #9137 this library isn't thread-safe
     fn test_loading_cosine() {
         // The math library does not need to be loaded since it is already
         // statically linked in
@@ -121,6 +122,7 @@ mod test {
     #[cfg(target_os = "linux")]
     #[cfg(target_os = "macos")]
     #[cfg(target_os = "freebsd")]
+    #[ignore] // FIXME #9137 this library isn't thread-safe
     fn test_errors_do_not_crash() {
         // Open /dev/null as a library to get an error, and make sure
         // that only causes an error, and not a crash.