i965/gs: Stop storing an input VUE map in the GS program key.

i965/gs: Stop storing an input VUE map in the GS program key.

Now that the vertex shader output VUE map is determined solely by a
64-bit bitfield, we don't have to store it in its entirety in the
geometry shader program key; instead, we can just store the bitfield,
and let the geometry shader infer the VUE map at compile time.

This dramatically reduces the size of the geometry shader program key,
which we want to keep small since it gets recomputed whenever the
active program changes.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>