intel/compiler: fine-grained control of dispatch widths

Reviewed-by: Matt Turner <mattst88@gmail.com> [v1]
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20535>

src/intel/compiler/test_simd_selection.cpp

@@ -51,6 +51,7 @@ protected:
       .prog_data = prog_data,
      }
    {
+      brw_process_intel_debug_variable();
    }
 
    ~SIMDSelectionTest() {