Fix SDL2 include paths

closes #96

source/Irrlicht/CIrrDeviceSDL.cpp

@@ -17,7 +17,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "SIrrCreationParameters.h"
-#include <SDL2/SDL_video.h>
+#include <SDL_video.h>
 
 #ifdef _IRR_EMSCRIPTEN_PLATFORM_
 #ifdef _IRR_COMPILE_WITH_OGLES2_

source/Irrlicht/CIrrDeviceSDL.h

@@ -20,8 +20,8 @@
 #include <emscripten/html5.h>
 #endif
 
-#include <SDL2/SDL.h>
-#include <SDL2/SDL_syswm.h>
+#include <SDL.h>
+#include <SDL_syswm.h>
 
 namespace irr
 {

source/Irrlicht/COpenGLCommon.h

@@ -39,8 +39,8 @@
 	#else
 		#define GL_GLEXT_PROTOTYPES 1
 	#endif
-	#include <SDL2/SDL_video.h>
-	#include <SDL2/SDL_opengl.h>
+	#include <SDL_video.h>
+	#include <SDL_opengl.h>
 	#if defined(_IRR_OPENGL_USE_EXTPOINTER_)
 		// The SDL2 header doesn't cut it for extensions
 		#include <GL/glext.h>

source/Irrlicht/os.cpp

@@ -8,7 +8,7 @@
 #include "irrMath.h"
 
 #if defined(_IRR_COMPILE_WITH_SDL_DEVICE_)
-	#include <SDL2/SDL_endian.h>
+	#include <SDL_endian.h>
 	#define bswap_16(X) SDL_Swap16(X)
 	#define bswap_32(X) SDL_Swap32(X)
 	#define bswap_64(X) SDL_Swap64(X)