glxinfo: handle no fbconfigs case better

If we get a server that has only GLX1.2 and no SGIX_fbconfig, we can
print stuff we shouldn't. If we have no fbconfigs then we don't have core
profile, so don't bother trying visual path when doing core profile.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
glxinfo: add GL 4.4 to the list