Revert "COmmon, xrCore: refactor SDL2 includes"

This reverts commit 56931f3.

Author: eagleivg

src/Common/Common.hpp

@@ -6,5 +6,12 @@
 #include "Common/FSMacros.hpp"
 #include "Include/xrAPI/xrAPI.h"
 
+#if defined(WINDOWS)
+#if __has_include("SDL.h")
 #include "SDL.h"
+#endif
+
+#if __has_include("SDL_syswm.h")
 #include "SDL_syswm.h"
+#endif
+#endif

src/xrCore/xrMemory.cpp

@@ -1,5 +1,7 @@
 #include "stdafx.h"
 
+#include "SDL.h"
+
 #if defined(WINDOWS)
 #include <Psapi.h>
 #elif defined(LINUX)