mesa: fix asst. issues in _mesa_texstore_argb8888()

If we shift bytes into the texel word (or use the PACK_COLOR_8888 macro),
we don't have to worry about big vs. little endian.  See comments about
texel formats in texformat.h.
Remove an unneeded/incorrect else-if clause that produced wrong results
on big-endian systems.
1 file changed