MT#55283 fix compiler warning

Change-Id: I93a6b99f699b697f3873bc9641c441d4749a520d
(cherry picked from commit 75abd43516)
(cherry picked from commit 4c33304883)

t/tests-preload.c

@@ -256,7 +256,7 @@ got_peer:
 	}
 	else if (path[0] == '[') {
 		path++;
-		char *end = strchr(path, ']');
+		const char *end = strchr(path, ']');
 		assert(end != NULL);
 		char addr[64];
 		if (snprintf(addr, sizeof(addr), "%.*s", (int) (end - path), path) >= sizeof(addr))