Reflection: Disable typeref_decoding_objc test on non-OS X platforms for now

Author: slavapestov

test/Reflection/typeref_decoding_objc.swift

@@ -3,3 +3,5 @@
 // RUN: %target-swift-reflection-dump -binary-filename %t/libTypesToReflect.%target-dylib-extension > %t/typeref_decoding.txt
 // RUN: diff -u %S/typeref_decoding_objc.result.txt %t/typeref_decoding.txt
 // REQUIRES: objc_interop
+
+// REQUIRES: OS=macosx