typesafe_cb: don't use HAVE_CAST_TO_UNION in tests.

This crept in, it should be the same as the tests in typesafe_cb.h.

ccan/typesafe_cb/test/compile_fail-typesafe_cb_cast-multi.c

@@ -29,7 +29,7 @@ int main(int argc, char *argv[])
 {
 #ifdef FAIL
 	struct other
-#if !HAVE_TYPEOF || !HAVE_CAST_TO_UNION
+#if !HAVE_TYPEOF||!HAVE_BUILTIN_CHOOSE_EXPR||!HAVE_BUILTIN_TYPES_COMPATIBLE_P
 #error "Unfortunately we don't fail if typesafe_cb_cast is a noop."
 #endif
 #else

ccan/typesafe_cb/test/compile_fail-typesafe_cb_cast.c

@@ -14,7 +14,7 @@ int main(int argc, char *argv[])
 #ifdef FAIL
 	int x = 0;
 	set_some_value(x);
-#if !HAVE_TYPEOF||!HAVE_CAST_TO_UNION
+#if !HAVE_TYPEOF||!HAVE_BUILTIN_CHOOSE_EXPR||!HAVE_BUILTIN_TYPES_COMPATIBLE_P
 #error "Unfortunately we don't fail if typesafe_cb_cast is a noop."
 #endif
 #else