nir/gather_info: recognize load_patch_vertices_in as a system value

This intrinsic is produced to load SYSTEM_VALUE_VERTICES_IN, which is
generated to load gl_PatchVerticesIn in the SPIR-V path for both
Vulkan and OpenGL.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/compiler/nir/nir_gather_info.c

@@ -246,6 +246,7 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader)
    case nir_intrinsic_load_tess_coord:
    case nir_intrinsic_load_tess_level_outer:
    case nir_intrinsic_load_tess_level_inner:
+   case nir_intrinsic_load_patch_vertices_in:
       shader->info.system_values_read |=
          (1ull << nir_system_value_from_intrinsic(instr->intrinsic));
       break;