The last use of pScreen in ProcXFixesSetPictureClipRegion was removed in
aa7096ca6f108e399d9916639cf20c57f9776305 so remove it entirely.
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>
Signed-off-by: Cyril Brulebois <kibi@debian.org>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>