MFC 264242,264244,264259

Fix panic on load new driver while vt(4) is in VGA textmode.
o Mute terminal while vt(4) driver change in progress.
o Reset VDF_TEXTMODE before init new driver.
o Assign default font, if new driver is not in TEXTMODE.
o Do not update screen while driver changing.
o Unmute terminal when done with driver replacement.
o Move init fonts to early point.
o Minor cleanup.
o Do not fill screen, while muted. (kern/subr_terminal.c)

Sponsored by:	The FreeBSD Foundation
MFC various fixes to the tools/regression/ tests.

- r262953 Fix m4 tests so that they run cleanly with prove.
- r262954 Fix printf tests so that they run cleanly with prove.
- r262959 Fix sed tests so that they run cleanly with prove.
- r262960 Fix yacc tests so that they run cleanly with prove.
- r262961 Fix pkill tests so that they run cleanly with prove.
- r262962 Fix ncal tests so that they run cleanly with prove.
- r263081 Fix lastcomm tests under amd64.
- r263082 Only run the make tests when make is fmake.
- r263083 Fix sa tests.
- r263084 Turn a test precondition into a skip in the mdconfig tests.
- r263085 Make the strerror tests work without libtap.
- r263087 Remove broken tests for eui64_line.
- r263221 Change etcupdate tests to return 1 on test failures.
- r263352 Make the priv test program exit with non-zero if any failures are detected.
- r263353 errx prepends the program name to the message; don't do it by hand.
- r263362 Include strings.h so that bpf_filter.c can be built in userland.
MFC r264345:

Amend r263891, by making clang default to DWARF2 debug info format for
all FreeBSD versions, not just 10.x and earlier.  Apparently too many
people seem to have trouble with post-1993 formats.

Also remove the related notes about messing with kernel configuration
files from UPDATING, which are now superfluous.

Requested by:	many
MFC r260866,260900,261960 (3 revisions; summarized below):
260866: Fix a bad comparison operator and fix dumpdev comment
260900: Dummy commit; show r260866 was in-part by Christoph Mallon
261960: Add zfsboot to bsdinstall(8) scripted interface
MFC: r264349

mdoc and spelling cleanup.
MFC: r264362

Remove stray .Nm macro.
MFC r263777: sh: Fix possible memory leaks and double frees with unexpected
SIGINT.
MFC refactoring of the *.test.mk files.

- r263161 Make bsd.test.mk the only public mk fragment for the building of tests.
- r263172 Move FreeBSD Test Suite-specific code to a suite.test.mk file.
- r263204 Add some documentation for bsd.test.mk.
- r263217 Document support for TAP-compliant Perl test programs.

This is "make tinderbox" clean.
MFC: 264016

Silence an unnecessary warning.
MFC r262812

- Gracefully handle truncation failures when trying to shrink directories.
  This could cause dirhash panics since the dirhash state would be
  successfully truncated while the directory was not.

Submitted by:   jeffr
MFC r262814

- If we fail to do a non-blocking acquire of a buf lock while doing a
  waiting sync pass we need to do a blocking acquire and restart.
  Another thread, typically the buf daemon, may have this buf locked and
  if we don't wait we can fail to sync the file.  This lead to a great
  variety of softdep panics because we rely on all dependencies being
  flushed before proceeding in several cases.

Submitted by:	jeffr
MFC r264229

Add some assertions to ensure that the target array doesn't get accessed
out of bounds.
MFC r261558

Add a new sysctl, dev.cxgbe.N.rsrv_noflow, and a companion tunable,
hw.cxgbe.rsrv_noflow.  When set, queue 0 of the port is reserved for
TX packets without a flowid.  The hash value of packets with a flowid
is bumped up by 1.  The intent is to provide a private queue for
link-level packets like LACP that is unlikely to overflow or suffer
deep queue latency.
MFC r263998:

Rename __wchar_t so it no longer conflicts with __wchar_t from clang 3.4
-fms-extensions.
MFC r263986:

- In the libiconv module for ISO 2022 restore the original order of the
  fields of a private struct such that variables of this type are
  initialised correctly.  Fixes conversion from ISO 2022.
  Also do this in the BIG5 module to prevent similar errors in the future.
- In the libiconv module for EUC-TW replace 2^cs with 1<<cs.  Fixes
  conversion from EUC-TW.
- Synchronise iconv code with NetBSD.  In most cases this only updates
  the RCS id because the changes are already there or are NetBSD specific.
  + libc/iconv/citrus_csmapper.c: Add a comment.
  + libc/iconv/citrus_db_factory.c: Remove put16().
  + libc/iconv/citrus_iconv.c: Return EINVAL on error.
  + libc/iconv/citrus_mapper.c: Return EINVAL on error.
  + libc/iconv/citrus_memstream.c: Fix type of a variable.
  + libc/iconv/citrus_prop.h: Sync definition of _CITRUS_PROP_HINT_END.
  + libc/iconv/citrus_stdenc.c: Return EINVAL on error.
  + libiconv_modules/mapper_std/citrus_mapper_std.c: Plug memory leak.

Obtained from:	NetBSD