hibernate-util: add missing assertion

src/shared/hibernate-util.c

@@ -408,6 +408,8 @@ static int get_proc_meminfo_active(unsigned long long *ret) {
         unsigned long long active;
         int r;
 
+        assert(ret);
+
         r = get_proc_field("/proc/meminfo", "Active(anon)", WHITESPACE, &active_str);
         if (r < 0)
                 return log_debug_errno(r, "Failed to retrieve Active(anon) from /proc/meminfo: %m");