spirv: Allow VRS with mesh shaders.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14291>

src/compiler/spirv/vtn_variables.c

@@ -1119,7 +1119,8 @@ vtn_get_builtin_location(struct vtn_builder *b,
       break;
    case SpvBuiltInPrimitiveShadingRateKHR:
       if (b->shader->info.stage == MESA_SHADER_VERTEX ||
-          b->shader->info.stage == MESA_SHADER_GEOMETRY) {
+          b->shader->info.stage == MESA_SHADER_GEOMETRY ||
+          b->shader->info.stage == MESA_SHADER_MESH) {
          *location = VARYING_SLOT_PRIMITIVE_SHADING_RATE;
          *mode = nir_var_shader_out;
       } else {