Fix crashes during rasterization fallback by avoiding _tnl_need_projected_coords

Fix crashes during rasterization fallback by avoiding _tnl_need_projected_coords
during fallbacks.  In one case, _swsetup_Wakeup had just been called, covering
the need there, and in the other case, we can simply exit the entire
radeonChooseVertexState function, knowing that it will be called again once we
leave the fallback.

Bugzilla #:	2516
Submitted by:	sroland