Remove the following files: libGL.*, libglx.* and libGLcore.*. The files are all over your system. I recommend to do an updatedb and then do things like "locate libGL" to find the files.
Locations in which to look are: /usr/lib, /usr/X11R6/lib/modules/extensions and /usr/X11R6/lib/modules/drivers and perhaps some other locations that may contain old mesa stuff.