Run ldconfig(8) rc script before building ports so
ld-elf.so.hints exists for pkg(8).

This is a direct commit to stable/9 as generate-release.sh
does not exist in head/.

PR:		186554
Sponsored by:	The FreeBSD Foundation
MFC r261400:
  Take exclusive lock only when lle isn't NULL. We don't need write access
  to lle in most cases.

MFC r261583:
  Unlock entry before retry.

Sponsored by:	Yandex LLC
MFC r261522:

Describe the use of a freebsd-boot GPT partition, brought up by Scot
Hetzel <swhetzel@gmail.com> on the -doc mailing list.

Also modify the Author section to be clear that I wrote the man page,
not gptboot.
MFC r261609:

Pull in upstream libcxxrt commit 8006101, which makes its cxxabi.h file
compilable just by itself.

PR:		kern/184019
MFC: r261447

Fix a typo.
MFC: r261339

MLINK ixgbe.4 to {if_ix.4, ix.4}.  An update for ixgbe.4
which deals with the "ix prefix being shared by two drivers"
situation is forthcoming.
[automated] Merge in upstream-github/stable/9