glsl, nir: Make ir_quadop_bitfield_insert a vectorized operation.

glsl, nir: Make ir_quadop_bitfield_insert a vectorized operation.

We would like to be able to combine

   result.x = bitfieldInsert(src0.x, src1.x, src2.x, src3.x);
   result.y = bitfieldInsert(src0.y, src1.y, src2.y, src3.y);
   result.z = bitfieldInsert(src0.z, src1.z, src2.z, src3.z);
   result.w = bitfieldInsert(src0.w, src1.w, src2.w, src3.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 four 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>