MFC r274073:
Follow-up to r255036; remove beforeinstall directives from bsdconfig(8)
Makefile's, fixing concurrent installworld (`make -j17 installworld').

Reviewed by: delphij
Thanks to: delphij, emaste

MFC r258355,258360,258400-258401,258406-258407,258418,258430,258439,258589-
258590,258592,258727-258728,258785, with the following descriptions:

Revisions 258400-258401,258406-258407,258590,258727-258728,258785:
+ Add a new `includes' module (see: bsdconfig includes -h) for exploring
the bsdconfig(8) API

Remaining revisions:
258592: Sort all the messages.subr files
258355: Fix typo in a comment in networking/device.subr
258360: Whitespace, style, and other changes in networking/device.subr
258418: Quote interface names for good measure in networking/device.subr
258430: Remove an unused line in networking/device.subr
258439: Minor bugfix to f_die() function in common.subr
258589: Minor bugfix to syscons_ttys module

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Perform some code consolidation and add some additional error
checking/reporting. (similar to SVN revisions 251905 and 251915)

Remove unnecessary loops, perform some code consolidation, and add some
additional error checking/reporting. (same thing going on here as SVN
r251905 -- just this time for the mouse module instead of console)

Lessen verbosity of "Exit" menutag items to appear more consistent across
menus from one module to the next.

Replacing "Exit this menu (returning to previous)" with "Exit this menu".

PR: ports/169316

Import bsdconfig(8) as a replacement for the post-install abilities of
deprecated sysinstall(8). NOTE: WITH_BSDCONFIG is currently required.

Submitted by: Devin Teske (dteske), Ron McDowell <rcm@fuzzwad.org>
Reviewed by: Ron McDowell <rcm@fuzzwad.org>
Approved by: Ed Maste (emaste)