325.08/325.15 change breaks Firefox layer acceleration

This change in the 325 series has caused a problem with Firefox layers acceleration:
Generate a BadMatch error when applications attempt to create GLX pixmaps using glXCreatePixmap() or glXCreateGLXPixmapWithConfigSGIX() and the pixmap’s depth doesn’t match that of the specified GLXFBConfig.

See the bug report here: 896287 - [Linux] nvidia driver 325.08 and above w/ layers acceleration fails with "ABORT: X_GLXCreatePixmap: BadMatch (invalid parameter attributes)"