gem_ctx_bad_exec: skip vebox when appropriate

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
diff --git a/tests/gem_ctx_bad_exec.c b/tests/gem_ctx_bad_exec.c
index f0f49c1..dadd663 100644
--- a/tests/gem_ctx_bad_exec.c
+++ b/tests/gem_ctx_bad_exec.c
@@ -106,6 +106,7 @@
 	igt_subtest("blt")
 		igt_assert(exec(fd, handle, I915_EXEC_BLT, ctx_id) != 0);
 #ifdef I915_EXEC_VEBOX
+	igt_require(gem_has_vebox(fd));
 	igt_subtest("vebox")
 		igt_assert(exec(fd, handle, I915_EXEC_VEBOX, ctx_id) != 0);
 #endif