This is what worked for me (Using Ubuntu 13.10):
$ sudo ln -s /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1 /usr/lib/x86_64-linux-gnu/libGL.so
This should work, but if you get an error like this:
ln: failed to create symbolic link ‘/usr/lib/x86_64-linux-gnu/libGL.so’: File exists
Try deleting the symlink or renaming it to something else and re-trying the above command. In my case it was pointing to an unknown file libGL.so.1.2.0
.