meson: use gtest protocol for gtest based tests when possible

With the `gtest` protocol meson will add some extra arguments to the
test to generate better junit results, which may be useful. This
protocol is only available in meson 0.55.0+, so keep using the default
`exitcode` protocol for meson older than that.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8484>

src/compiler/meson.build

@@ -81,6 +81,7 @@ if with_tests
       dependencies : [dep_thread, idep_gtest, idep_nir, idep_mesautil],
     ),
     suite : ['compiler', 'spirv'],
+    protocol : gtest_test_protocol,
   )
 
   test(
@@ -94,6 +95,7 @@ if with_tests
       dependencies : [dep_thread, idep_gtest, idep_nir, idep_mesautil],
     ),
     suite : ['compiler', 'spirv'],
+    protocol : gtest_test_protocol,
   )
 endif