Now that all supported FreeBSD versions support libmap.conf files installed
from ports, remove the symlink dance with libGL/libEGL/libgles and the
nvidia-driver ports.

• Revert libGL/libEGL/libglesv2 ports to normal.
• Rename the conflicting libraries from the nvidia-driver ports with a -NVIDIA prefix and install a libmap.conf file to map to these versions.
• Remove the special case from Mk/Scripts/qa.sh for libGL and libEGL.
• Sadly the symlink dance between nvidia-driver and xorg-server for glx.so need to stay, due to xorg-server opening that file with dlopen(3).

Approved by: portmgr@ (mat@ (prio version))
Differential Revision: https://reviews.freebsd.org/D7848