Don't attempt to build gltests nor OGLSuperBible directories.
Don't attempt to build gltests nor OGLSuperBible directories.

These directories were recently removed in a git-filter-branch rewrite
of the Vogl history (as part of an effort to reduce repository size).
Since these directories no longer exist, we cannot build them.

kingtaurus/vogl,bclemetsonblizzard/vogl,kingtaurus/vogl,kingtaurus/vogl,ValveSoftware/vogl,bclemetsonblizzard/vogl,bclemetsonblizzard/vogl,kingtaurus/vogl,bclemetsonblizzard/vogl,bclemetsonblizzard/vogl,ValveSoftware/vogl,ValveSoftware/vogl,ValveSoftware/vogl