It looks to me like the problem was with xorg-driver-fglrx, which still had some diversions registered for /usr/lib32/libGL.so.1.2 and /usr/lib/libGL.so.1.2 despite it no longer being a real package. So when fglrx tried to restore the libGL.so stuff it failed causing the entire uninstall to fail.
I resolved the problem by forcing a reinstall of fglrx then manually running:
sudo dpkg-divert --remove /usr/lib32/libGL.so.1.2
sudo dpkg-divert --remove /usr/lib/libGL.so.1.2
Then I was able to uninstall fglrx successfully.
VDPAU still isn't working even with the newer fglrx driver, but that's a different problem I believe.
It looks to me like the problem was with xorg-driver-fglrx, which still had some diversions registered for /usr/lib32/ libGL.so. 1.2 and /usr/lib/ libGL.so. 1.2 despite it no longer being a real package. So when fglrx tried to restore the libGL.so stuff it failed causing the entire uninstall to fail.
I resolved the problem by forcing a reinstall of fglrx then manually running: libGL.so. 1.2 libGL.so. 1.2
sudo dpkg-divert --remove /usr/lib32/
sudo dpkg-divert --remove /usr/lib/
Then I was able to uninstall fglrx successfully.
VDPAU still isn't working even with the newer fglrx driver, but that's a different problem I believe.