I still have this bug with the latest nvidia-glx-180. In /usr/lib/xorg/modules/extensions the symlink to libglx.so.180.44 is made, but in /usr/lib/xorg/modules/ it still links to the old module /usr/lib/xorg/modules/extensions/libglx.so.180.37 which doesn´t exist anymore.
I still have this bug with the latest nvidia-glx-180. In /usr/lib/ xorg/modules/ extensions the symlink to libglx.so.180.44 is made, but in /usr/lib/ xorg/modules/ it still links to the old module /usr/lib/ xorg/modules/ extensions/ libglx. so.180. 37 which doesn´t exist anymore.