systat adding -d altqs
Persist vdev_resilver_txg changes to avoid panic caused by validation
vs a vdev_resilver_txg value from a previous resilver.

MFC after:	1 week
systat add -altqs mode, ifstat update + man page
Add Reset Manager driver. This driver provides generic way to reset
and provides sysctl tunables for enable/disable FPGA<->HPS bridges.

Sponsored by:	DARPA, AFRL
Merge upstream Clang rev 205331 debuginfo crash fix:

    Debug info: fix a crash when emitting IndirectFieldDecls, which were
    previously not handled at all.
    rdar://problem/16348575

MFC after:	1 week
Sponsored by:	DARPA, AFRL
Add clang patch corresponding to r271432
Update motd, clarifying the information and adding pointers to other
resources.

MFC after:	3 days
sysctl, various ERANGE checking as you can get overflow with numeric values (for example ker.maxfiles > INT_MAX leads to -1...)
ls ... when it relies on env vars like COLUMNS which can be ... anything ! when it gets wrong back to default value
same flavor than ls for COLUMNS/LINES env vars...
pax options small errno check for block size
error checking for timeout values
errno check for columns size
COLUMNS env var handling again
errno checking for metric/mtu parameters
termwidth value errno checking
fstat pid errno checking
gcore pid checking
pid errno checkings
Fix typo.

MFC after:	3 days
Sponsored by:	The FreeBSD Foundation