wine.inf: Register iexplore from the system directory so that the 32-bit version gets registered too.

This code was needed when the destination uses 8-bit and the source lacked a palette.
Since we don't allow destination fixups, this code doesn't do anything. At a later
stage something like this should perhaps be readded to specific backends.

winex11: Rewrite AlphaBlend to do everything on the server side, and support all types of source bitmaps.