configurator: HAVE_ATTRIBUTE_RETURNS_NONNULL

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tools/configurator/configurator.c

@@ -142,6 +142,9 @@ static const struct test base_tests[] = {
 	{ "HAVE_ATTRIBUTE_NONNULL", "__attribute__((nonnull)) support",
 	  "DEFINES_FUNC", NULL, NULL,
 	  "static char *__attribute__((nonnull)) func(char *p) { return p; }" },
+	{ "HAVE_ATTRIBUTE_RETURNS_NONNULL", "__attribute__((returns_nonnull)) support",
+	  "DEFINES_FUNC", NULL, NULL,
+	  "static const char *__attribute__((returns_nonnull)) func(void) { return \"hi\"; }" },
 	{ "HAVE_ATTRIBUTE_SENTINEL", "__attribute__((sentinel)) support",
 	  "DEFINES_FUNC", NULL, NULL,
 	  "static int __attribute__((sentinel)) func(int i, ...) { return i; }" },