Fixed Mac OS X build
diff --git a/include/SDL_opengl_glext.h b/include/SDL_opengl_glext.h
index d520a8a..d59fc09 100644
--- a/include/SDL_opengl_glext.h
+++ b/include/SDL_opengl_glext.h
@@ -465,8 +465,13 @@ GLAPI void APIENTRY glBlendEquation (GLenum mode);
#ifndef GL_VERSION_1_5
#define GL_VERSION_1_5 1
#include <stddef.h>
+#ifdef __MACOSX__
+typedef ssize_t GLsizeiptr;
+typedef ssize_t GLintptr;
+#else
typedef ptrdiff_t GLsizeiptr;
typedef ptrdiff_t GLintptr;
+#endif
#define GL_BUFFER_SIZE 0x8764
#define GL_BUFFER_USAGE 0x8765
#define GL_QUERY_COUNTER_BITS 0x8864