Add a new release build variable, WITH_COMPRESSED_IMAGES.

When set to a non-empty value, the installation medium is
compressed with gzip(1) as part of the 'install' target in
the release/ directory.

With gzip(1) compression, downloadable image are reduced in
size quite significantly.  Build test against head@263927
shows the following:

 bootonly.iso:		64% smaller
 disc1.iso:		44% smaller
 memstick.img:		47% smaller
 mini-memstick.img:	65% smaller
 dvd1.iso:		untested

This option is off by default, I would eventually like to
turn it on by default, and remove the '-k' flag to gzip(1)
so only compressed images are published on FTP.

Requested by:	wkoszek
MFC After:	1 week
Sponsored by:	The FreeBSD Foundation
Clean up trailing whitespace in release/Makefile.

MFC after:	1 week
X-MFC-With:	r264027
Sponsored by:	The FreeBSD Foundation
Fix logic error: s/||/&&/

Pointyhat:	gjb
MFC after:	1 week
X-MFC-With:	r264027,r264028
Sponsored by:	The FreeBSD Foundation
If WITH_COMPRESSED_IMAGES is set, add the compressed images to
the CLEANFILES list.

MFC after:	1 week
X-MFC-With:	r264027,r264028,r264029
Sponsored by:	The FreeBSD Foundation
Use 2K buffers for IO to help achieve full device speed, rather than the
default wMaxPacketSize (64 or 512 bytes).  This actually helps older FTDI
devices (which were USB 1/full speed) more than the new H-series high
speed, but even for the new chips it helps cut the number of interrupts
when doing very high speed (3-12mbaud).
Fix an issue where the locale and rune locale could become out of sync,
causing mb* functions (and similar) to be called with the wrong data
(possibly a null pointer, causing a crash).

PR:		standards/188036
MFC after:	1 week
Document more parition types.

Requested by:	glebius
MFC after:	1 week
MFV	r258379;

4248 dtrace(1M) should never create DOF with empty probes section
4249 Only probes from the first DTrace object file will be included

Illumos Revision:	4a20ab41aadcb81c53e72fc65886e964e9add59

Reference:
https://www.illumos.org/issues/4248
https://www.illumos.org/issues/4249

Obtained from:	Illumos
MFC after:	1 month
Add support for event timers whose clock frequency can change while running.
Add support for some block functions that come from OS X.  These are
intended to build with any C compiler.

Reviewed by:	pfg
MFC after:	3 weeks
Move scandir_b to a later symbol version.
FreeBSD make (aka fmake) doesn't grok .MAKE.LEVEL. Failsafe and assume
that it is OK to set MK_xxx flags.
Move setting of the MK_xxx variables based on NO_xxx to avoid
triggering the "you aren't allowed to set this" warning when building
stand alone in directories whose Makefile sets NO_MAN, for example.
Use xz(1) instead of gzip(1) to compress release images
when WITH_COMPRESSED_IMAGES is used.

Requested by:	delphij, brooks, Nikolai Lifanov
MFC After:	1 week
X-MFC-With:	r264027,r264028,r264029,r264030
Sponsored by:	The FreeBSD Foundation
Fix build breakage.  Apparently all ARM configs build kern_et.c, but only a
few of them also build kern_clocksource.c.  That strikes me as insane, but
maybe there's a good reason for it.  Until I figure that out, un-break
the build by not referencing functions in kern_clocksource if NO_EVENTTIMERS
is defined.
Disable the timer and clear any pending bit, then setup the new counter
register values, then restart the timer.  This prevents a situation where
an old event fires just as we're about to load a new value into the timer,
when the start routine is called to change the time of the current event.

Also re-nest the parens properly for casting the result of converting
time and frequency to a count.  This doesn't actually change the result of
the calcs, but will some day prevent a loss-of-precision warning on the
assignment, if that warning gets enabled.
Trivial changes/forced-commit to document previous change r264050 whose
description was eaten by the dog (or an editor crash or something).

Add variable-frequency support to the arm mpcore eventtimer driver.

This allows a platform's early init code to tell the mpcore driver that the
clock frequency can vary.  That causes the mpcore driver to register an
eventtimer, but not a timecounter.  The platform has to provide a time
counter using some other fixed-frequency clock, but can still use the
per-cpu goodness of the mpcore hardware for event timers.

When the platform support code does something to change the frequency of
the CPU clocks (power saving, thermal management) it must tell the mpcore
driver code about it using arm_tmr_change_frequency().
Don't call sdhci_init_slot() until after handling the FDT properties
related to detecting card presence.  This actually makes no difference
now, but will when we get support for gpio-based card detection.
Change NO_EVENTTIMERS from an arm-specific to an MI option, so that it can
be used in MI code.

This is intended as a temporary measure to unbreak the build.  The real fix
is to write event timer drivers for legacy arm hardware, then get rid of
this option completely.  That's going to take a few days.