Add _mac suffix for obj-c files.

browser/atom_application_delegate_mac.h

@@ -0,0 +1,13 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <Cocoa/Cocoa.h>
+
+@interface AtomApplicationDelegate : NSObject<NSApplicationDelegate> {
+}
+
+- (void)handleQuitEvent:(NSAppleEventDescriptor*)event
+         withReplyEvent:(NSAppleEventDescriptor*)replyEvent;
+
+@end