MFC 225096:

MFC 225096:
Fix if_addr_mtx recursion in mld6.

mld_set_version() is called only from mld_v1_input_query() and
mld_v2_input_query() both holding the if_addr_mtx lock, and then calling
into mld_v2_cancel_link_timers() acquires it the second time, which results
in mtx recursion. To avoid that, delay if_addr_mtx acquisition until after
mld_set_version() is called; while here, further reduce locking scope
to protect only the needed pieces: if_multiaddrs, in6m_lookup_locked().

git-svn-id: svn://svn.freebsd.org/base/stable/8@233199 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f