Evas test matrix: Silence warning.

This happens because this test doesn't really depend on anything evas,
so it doesn't set evas up. We want to be warned when tests forget to set
evas up, just not in this case.

src/tests/evas/evas_test_matrix.c

@@ -37,5 +37,6 @@ END_TEST
 
 void evas_test_matrix(TCase *tc)
 {
+   (void) _setup_evas;
    tcase_add_test(tc, evas_matrix);
 }