Avoid possible lock leaking. After r343619 ipfw uses own locking for packets flow. PULLUP_LEN() macro is used in ipfw_chk() to make m_pullup(). When m_pullup() fails, it just returns via `goto pullup_failed`. There are two places where PULLUP_LEN() is called with IPFW_PF_RLOCK() held. Add PULLUP_LEN_LOCKED() macro to use in these places to be able release the lock, when m_pullup() fails. Sponsored by: Yandex LLC NOTE: since r343619 was not merged, this commit is mostly NOP, but it is needed to reduce code difference between stable and head/.