Make internal SDL sources include SDL_internal.h instead of SDL_config.h

The new header will include SDL_config.h, but allows for other global stuff.

--HG--
extra : rebase_source : ddf4a4c0dc2c554b98c82700798f343cd91b16e3

src/SDL_internal.h

@@ -0,0 +1,28 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#ifndef _SDL_internal_h
+#define _SDL_internal_h
+
+#include "SDL_config.h"
+
+#endif
+
+/* vi: set ts=4 sw=4 expandtab: */