* Implement libGL as a symlink package which uses libraries from libglvnd and
headers from Mesa (since ones from libglvnd are outdated).
* Use libGL_driver.driverLink treewide; add FHS paths where possible.
I updated the erlang esdl lib, added the erlang cl lib,
added opencl-headers and ocl-icd to make wings build and run.
I have not tested its opencl part; I only added dependencies so
it builds.
