meson: add nir_linking_helpers.c to libnir

This was missed in a rebase, and doesn't affect radv or anv, only i965.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/compiler/nir/meson.build

@@ -90,6 +90,7 @@ files_libnir = files(
   'nir_instr_set.h',
   'nir_intrinsics.c',
   'nir_intrinsics.h',
+  'nir_linking_helpers.c',
   'nir_liveness.c',
   'nir_loop_analyze.c',
   'nir_loop_analyze.h',