demos: spiv: Handle transparent images better.

* Remove the workaround that converts all images to RGB888.
   - the Resize filters now can handle all pixel formats
     (minus the cubic float, but who cares about this one anyway)

* Fill the buffer with chessboard-like pattern before blit
  image with transparency.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
gfxprim_config.py: Remove a few odd pixel types.

This just cleanups the config (and some of the code) and removes a few
odd pixel types.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
install: Hack /usr/lib vs /usr/lib64 detection.

This should fix installation on Fedora until we made proper
'make install' for the C library.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>