Instead of complex wrap/unwrap trickery in the error path, just
protect the DestroyPixmap() handlers from half-initialized state.
Prior to this change, we always had to make sure, the we're calling
the original (screen driver's) handler directly, instead of our own
(which calls the original one, too), so it doesn't do any damage.
This isn't necessary anymore, since it finds out on it own what to do.
This not just makes the code flow simpler and easier to understand, but
also clears the road for decoupling the extension specific pixmap destructor
logic from the ScreenRec proc vectors (*1).
*1) see: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1755https://gitlab.freedesktop.org/xorg/xserver/-/issues/1754
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1711>
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