cursor: drop ARGB_CURSOR

I doubt anyone builds with this turned off or has done for a long
time.

It helps my eyes bleed slightly less when reading the code, I've left
the define in place as some drivers use it.

Reviewed-by: Aaron Plattner <aplattner@nvidia.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

xfixes/cursor.c

@@ -306,11 +306,9 @@ CopyCursorToImage(CursorPtr pCursor, CARD32 *image)
     int height = pCursor->bits->height;
     int npixels = width * height;
 
-#ifdef ARGB_CURSOR
     if (pCursor->bits->argb)
         memcpy(image, pCursor->bits->argb, npixels * sizeof(CARD32));
     else
-#endif
     {
         unsigned char *srcLine = pCursor->bits->source;
         unsigned char *mskLine = pCursor->bits->mask;