Update Subversion and dependencies to 1.14.0 LTS.

MFC r323365 (by jonathan):

Remove redundant source and object files.

Reviewed by: bdrewery, ngie
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D12208

MFC r327739 (by asomers):

Add Pull Request to the Subversion commit template

Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D13178

MFC r333354 (by peter):

Update svn-1.9.7 to 1.10.0.

MFC r333355 (by peter):

Update svn/svnlite from 1.9.7 to 1.10.0

MFC r333387 (by peter):

Update svn_private_config.h - I misread an autoconf change.
SVN_LIBSVN_CLIENT_LINKS_RA_LOCAL -> SVN_LIBSVN_RA_LINKS_RA_LOCAL
SVN_LIBSVN_CLIENT_LINKS_RA_SERF -> SVN_LIBSVN_RA_LINKS_RA_SERF
SVN_LIBSVN_CLIENT_LINKS_RA_SVN -> SVN_LIBSVN_RA_LINKS_RA_SVN

MFC r339256 (by jhb):

Update Apache Serf to 1.3.9 to support OpenSSL 1.1.1.

Approved by: re (rgrimes)

MFC r352156 (by imp):

Remove directory empty after r266735

MFC r357299 (by cem):

contrib/apr: Remove scope leak UB

In apr_vformatter, the variable buf was declared inside a limited scope
region, but a pointer to it is leaked outside of that region and used
later. This is undefined behavior. Fix by moving the buf variable to
function scope.

Reported by: Coverity
CID: 1192541

MFC r357301 (by cem):

contrib/apr: Rip out bogus [CS]PRNG implementation

This construction used some relatively slow design involving SHA2; even if
it were fed real entropy (unclear; external to the design), it did not
handle fork in a safe way, and it was difficult to audit for correctness.
So just rip it out and use the very simple and known-correct arc4random(3)
interface in its place.

MFC r361677:

Change Makefiles under usr.bin/svn to make them easier to incrementally
update. No functional change intended.

MFC r361678:

Update apr to 1.7.0. See contrib/apr/CHANGES for a summary of changes.

MFC r361681:

Change more Makefiles under usr.bin/svn to make them easier to
incrementally update. No functional change intended.

MFC r361684 (by kevans):

apr: build some needed emulated 64-bit atomic bits after r361678

This should fix the build on armv{6,7}, mips, and mips64, which all need
emulated 64-bit atomics for apr.

MFC r361691:

Follow-up r361678 (update apr to 1.7.0) by also regenerating the apr
internal headers through the upstream configure script, with some minor
custom tweaks.

MFC r361692:

Update apr-util to 1.6.1. See contrib/apr-util/CHANGES for a summary of
changes.

MFC r361693:

Update Subversion to 1.14.0 LTS. See contrib/subversion/CHANGES for a
summary of changes, or for a more thorough overview:

https://subversion.apache.org/docs/release-notes/1.14

NOTE: there is no need to dump and reload repositories, and the working
copy format is still the same as Subversion 1.8 through 1.13.

Relnotes: yes

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Introduce svnlite so that we can check out our source code again.

This is actually a fully functional build except:
* All internal shared libraries are static linked to make sure there
is no interference with ports (and to reduce build time).
* It does not have the python/perl/etc plugin or API support.
* By default, it installs as "svnlite" rather than "svn".
* If WITH_SVN added in make.conf, you get "svn".
* If WITHOUT_SVNLITE is in make.conf, this is completely disabled.

To be absolutely clear, this is not intended for any use other than
checking out freebsd source and committing, like we once did with cvs.

It should be usable for small scale local repositories that don't
need the python/perl plugin architecture.

Import apache apr-1.4.6