(640x480 fullscreen -> windowed would give a large 1280x768 window mostly filled with garbage).
Previously, we were only using the fast path on old systems (no VBO support) anyway.
git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@1272 af15c1b1-3010-417e-b628-4374ebc0bcbd