glsl, nir: Make ir_triop_bitfield_extract a vectorized operation.

glsl, nir: Make ir_triop_bitfield_extract a vectorized operation.

We would like to be able to combine

   result.x = bitfieldExtract(src0.x, src1.x, src2.x);
   result.y = bitfieldExtract(src0.y, src1.y, src2.y);
   result.z = bitfieldExtract(src0.z, src1.z, src2.z);
   result.w = bitfieldExtract(src0.w, src1.w, src2.w);

into a single ivec4 bitfieldInsert operation.  This should be possible
with most drivers.

This patch changes the offset and bits parameters from scalar ints
to ivecN or uvecN.  The type of all three operands will be the same,
for simplicity.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>