MFC r254237:
Add optional support for default override of standard setup; but only if
corresponding functions are provided. If override function does not exist,
boot remains unmodified. This patch should not result in any changes.
MFC r253853:
  Include /usr/local/etc/libmap.d/ by default.

  PR:             180568
  Reviewed by:    bapt
  Obtained from:  kib
MFC r253986:
  Fix formatting warning.
MFC: Temporarily revert sendmail 8.14.7 change to getipnodebyname() flags
     to prevent problems between the resolver and Microsoft DNS servers with
     AAAA lookups.  The upstream open source project will work on a more
     permanent fix for the next release.  Issue noted by Pavel Timofeev.
MFC r254338:
Don't send uninitialized memory (two instances of 4 bytes) in
every cookie on the wire. This bug was reported in
https://bugzilla.mozilla.org/show_bug.cgi?id=905080
MFC: r254091

According to POSIX \ in the fnmatch(3) pattern should escape
any character including '\0', but our version replace escaped '\0'
with '\\'.
I.e. fnmatch("\\", "\\", 0) should not match while fnmatch("\\", "", 0)
should (Linux and NetBSD does the same). Was vice versa.

PR:     181129
Merge remote-tracking branch 'upstream-github/stable/9' into stable/9