Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r266728,266731,266735,266736,268135,268960,269833
Update apr 1.4.8 -> 1.5.1
Update apr-util 1.5.2 -> 1.5.3
Update serf 1.3.4 -> 1.3.7
Update svnlite 1.8.8 -> 1.8.10
Deal with svnlite.1 manpage.

Merge apr-1.4.8 -> apr-1.5.1 and update.

Vendor import apr-1.5.1