Add more endian-specific aliases for 32 bit pixelformats

Add these for all the RGBX variants, just like all the RGBA variants already have.

include/SDL3/SDL_pixels.h

@@ -263,11 +263,19 @@ typedef enum
     SDL_PIXELFORMAT_ARGB32 = SDL_PIXELFORMAT_ARGB8888,
     SDL_PIXELFORMAT_BGRA32 = SDL_PIXELFORMAT_BGRA8888,
     SDL_PIXELFORMAT_ABGR32 = SDL_PIXELFORMAT_ABGR8888,
+    SDL_PIXELFORMAT_RGBX32 = SDL_PIXELFORMAT_RGBX8888,
+    SDL_PIXELFORMAT_XRGB32 = SDL_PIXELFORMAT_XRGB8888,
+    SDL_PIXELFORMAT_BGRX32 = SDL_PIXELFORMAT_BGRX8888,
+    SDL_PIXELFORMAT_XBGR32 = SDL_PIXELFORMAT_XBGR8888,
 #else
     SDL_PIXELFORMAT_RGBA32 = SDL_PIXELFORMAT_ABGR8888,
     SDL_PIXELFORMAT_ARGB32 = SDL_PIXELFORMAT_BGRA8888,
     SDL_PIXELFORMAT_BGRA32 = SDL_PIXELFORMAT_ARGB8888,
     SDL_PIXELFORMAT_ABGR32 = SDL_PIXELFORMAT_RGBA8888,
+    SDL_PIXELFORMAT_RGBX32 = SDL_PIXELFORMAT_XBGR8888,
+    SDL_PIXELFORMAT_XRGB32 = SDL_PIXELFORMAT_BGRX8888,
+    SDL_PIXELFORMAT_BGRX32 = SDL_PIXELFORMAT_XRGB8888,
+    SDL_PIXELFORMAT_XBGR32 = SDL_PIXELFORMAT_RGBX8888,
 #endif
 
     SDL_PIXELFORMAT_YV12 =      /**< Planar mode: Y + V + U  (3 planes) */