use atomic_fetchadd_int in m_mclfree()

[Matthew Dillon]

:Hi all,
:
:Following patch uses atomic_fetchadd_int to simplify the reference
:logic in m_mclfree()
:http://leaf.dragonflybsd.org/~sephe/mbuf_fetchadd.diff
:
:Best Regards,
:sephe

    Looks good.  It sure simplifies things!

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>