Removed check for _HAVE_STDINT_H

Fixes https://github.com/libsdl-org/SDL/issues/6619

include/SDL_config.h.cmake

@@ -517,7 +517,7 @@
 #cmakedefine SDL_VIDEO_VITA_PVR @SDL_VIDEO_VITA_PVR@
 #cmakedefine SDL_VIDEO_VITA_PVR_OGL @SDL_VIDEO_VITA_PVR_OGL@
 
-#if !defined(_STDINT_H_) && (!defined(HAVE_STDINT_H) || !_HAVE_STDINT_H)
+#if !defined(HAVE_STDINT_H) && !defined(_STDINT_H_)
 /* Most everything except Visual Studio 2008 and earlier has stdint.h now */
 #if defined(_MSC_VER) && (_MSC_VER < 1600)
 typedef signed __int8 int8_t;