Do not resolve glx functions specified in GLX 1.3

According to the OpenGL ABI for Linux GLX 1.3 is a minimum requirement.
Therefore we do not need to resolve the symbols which are present in that
version.

KWin did always require at least 1.3, for all the resolved functions
there were checks in the Scene, but they might have been incorrect.
Instead now the GLX version is checked and OpenGL compositing is blocked
if there is not at least GLX 1.3.

REVIEW: 106704