Reduce the disc1.iso image size by setting WITHOUT_CLANG=1 for the
'system' target.  Since clang is not enabled by default for releng/9.2,
this has no user visible changes by default.

This brings 9.2-R* well enough below the 700MB mark so that we do not
need to be concerned with it fitting on standard CD-ROM medium.

This is a direct commit to releng/9.2, pending further review for head/
and stable/9/.

Discussed with:	delphij, hrs
Approved by:	re (marius)
Sponsored by:	The FreeBSD Foundation
MFS of 255104:
MFC of 253998:

This bug fix is in a code path in rename taken when there is a
collision between a rename and an open system call for the same
target file. Here, rename releases its vnode references, waits for
the open to finish, and then restarts by reacquiring its needed
vnode locks. In this case, rename was unlocking but failing to
release its reference to one of its held vnodes. The effect was
that even after all the actual references to the vnode had gone,
the vnode still showed active references. For files that had been
removed, their space was not reclaimed until the filesystem was
forcibly unmounted.

This bug manifested itself in the Postgres server which would
leak/lose hundreds of files per day amounting to many gigabytes of
disk space. This bug required shutting down Postgres, forcibly
unmounting its filesystem, remounting its filesystem and restarting
Postgres every few days to recover the lost space.

Reported by: Dan Thomas and Palle Girgensohn
Bug-fix by:  kib
Tested by:   Dan Thomas and Palle Girgensohn

Approved by: re@ (Marius Strobl <marius@freebsd.org>)
MFS9 r255306:
MFC r245428:

Add CLOCK_PROCESS_CPUTIME_ID to <time.h>, to synchronize the CLOCK_*
values with those in <sys/time.h>.  Otherwise, if a program includes
<time.h> before <sys/time.h>, the CLOCK_PROCESS_CPUTIME_ID macro never
gets defined.

Reviewed by:	davidxu
Approved by:	re (kib)
MFH (r254684, r254955): fix segfault on reload.
MFH (r255156): silence an error message on non-IPv6 interfaces.

Approved by:    re (glebius)
MFH (r255243): create /var/authpf with correct ownership and permissions.

Approved by:	re (glebius)