Make header include guards great again

i.e. #ifndef VM_WHATEVER -> #ifndef RUNTIME_VM_WHATEVER

This lets us remove a hack from the PRESUBMIT.py script that existed
for reasons that are no longer valid, and sets us up to add some
presubmit checks for the GN build.

R=asiva@google.com, rmacnak@google.com

Review URL: https://codereview.chromium.org/2450713004 .

runtime/vm/native_message_handler.h

@@ -2,8 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#ifndef VM_NATIVE_MESSAGE_HANDLER_H_
-#define VM_NATIVE_MESSAGE_HANDLER_H_
+#ifndef RUNTIME_VM_NATIVE_MESSAGE_HANDLER_H_
+#define RUNTIME_VM_NATIVE_MESSAGE_HANDLER_H_
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
@@ -38,4 +38,4 @@ class NativeMessageHandler : public MessageHandler {
 
 }  // namespace dart
 
-#endif  // VM_NATIVE_MESSAGE_HANDLER_H_
+#endif  // RUNTIME_VM_NATIVE_MESSAGE_HANDLER_H_