lib: add a define for test failure exit status

Signed-off-by: Thomas Wood <thomas.wood@intel.com>

tests/gem_ring_sync_copy.c

@@ -317,7 +317,7 @@ static void run_test(data_t *data, enum ring r1, enum ring r2, enum test test)
 		bo_check(data, b, 0xc);
 		break;
 	default:
-		igt_fail(1);
+		igt_fail(IGT_EXIT_FAILURE);
 	}
 
 	r1_ops->busy_fini(data);

tests/kms_sink_crc_basic.c

@@ -100,7 +100,7 @@ static void assert_color(char *crc, enum color color)
 			   (bh & mask) == 0);
 		break;
 	default:
-		igt_fail(-1);
+		igt_fail(IGT_EXIT_FAILURE);
 	}
 }