i965: Print input/output VUE maps on INTEL_DEBUG=vs, gs.

i965: Print input/output VUE maps on INTEL_DEBUG=vs, gs.

I've been carrying around a patch to do this for the last few months,
and it's been exceedingly useful for debugging GS and tessellation
problems.  I've caught lots of bugs by inspecting the interface
expectations of two adjacent stages.

It's not that much spam, so I figure we may as well just print it.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Matt Turner <mattst88@gmail.com>