sh(1): Add/improve information about exit status of commands.
Constantly indent struct pagerops.
Even better indent struct pagerops.
Use ${SYSDIR} as the reference pointer instead of specifying relative path directly.

Reported by:	jenkins via Olivér Pintér (on github)
Reference uefi(8) from i386 boot(8)

Suggested by trasz.

Differential Revision: https://reviews.freebsd.org/D1162
Cleanup trailing newlines noticed while looking for other issues.
Automate options INET/INET6 turning into MK_$opt_SUPPORT
correctly. Fixes if_gfe when building without INET6 and
simplifies if_gif's Makefile.

Sponsored by: Netflix, Inc
Remove mostly obsolete hint to disable LAPIC timers.

It is partially covered by new code and partially by new CPUs.

PR:		195016
Submitted by:	tobias.rehbein@web.de
MFC after:	1 week