Add REQUIRES for noncopyable-captures.swift.

Author: rjmansfield

test/embedded/noncopyable-captures.swift

@@ -1,6 +1,8 @@
 // RUN: %target-swift-emit-ir %s -DIGNORE_FAILS -enable-experimental-feature Embedded -wmo -o /dev/null
 // RUN: %target-swift-emit-ir %s -enable-experimental-feature Embedded -wmo -verify
 
+// REQUIRES: OS=macosx || OS=linux-gnu
+
 struct MyStruct<Item> : ~Copyable {
     var member = "42"