Replace all include guard ifdefs with "#pragma once"

Source/Core/VideoBackends/D3D/Globals.h

@@ -2,13 +2,10 @@
 // Licensed under GPLv2
 // Refer to the license.txt file included.
 
-#ifndef _GLOBALS_H_
-#define _GLOBALS_H_
+#pragma once
 
 #include "Common.h"
 #include "VideoConfig.h"
 #include "main.h"
 
 #include "VideoCommon.h"
-
-#endif // _GLOBALS_H_