opt: fix gcc -O3 warnings.

ccan/opt/test/run-iter.c

@@ -20,7 +20,7 @@ static void reset_options(void)
 /* Test iterators. */
 int main(int argc, char *argv[])
 {
-	unsigned j, i, len;
+	unsigned j, i, len = 0;
 	const char *p;
 
 	plan_tests(37 * 2);

ccan/opt/test/utils.c

@@ -35,7 +35,9 @@ static void save_err_output(const char *fmt, ...)
 	char *p;
 
 	va_start(ap, fmt);
-	vasprintf(&p, fmt, ap);
+	/* Check return, for fascist gcc */
+	if (vasprintf(&p, fmt, ap) == -1)
+		p = NULL;
 	va_end(ap);
 
 	if (err_output) {