nir: Move nir_lower_uniforms_to_ubo to compiler/nir.

The nir_lower_uniforms_to_ubo function is useful outside of
mesa/state_tracker, and in fact is needed to produce NIR for
drivers that have the PIPE_CAP_PACKED_UNIFORMS capability.

Signed-Off-By: Timur Kristóf <timur.kristof@gmail.com>
Tested-by: Andre Heider <a.heider@gmail.com>
Tested-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/compiler/nir/meson.build

@@ -150,6 +150,7 @@ files_libnir = files(
   'nir_lower_wpos_center.c',
   'nir_lower_wpos_ytransform.c',
   'nir_lower_bit_size.c',
+  'nir_lower_uniforms_to_ubo.c',
   'nir_metadata.c',
   'nir_move_load_const.c',
   'nir_move_vec_src_uses_to_dest.c',