Merge apr-util 1.5.3 -> 1.5.4.  A minor bug fix update.
cxgbe/tom:  Catch up with r271119, syncache_add doesn't need tcbinfo lock.
Update comment (missed this bit in r272079).
Catch up with r271119.
Merge remote-tracking branch 'freebsd/master' into hardened/current/segvguard