Install a temporary workaround to avoid problems in fdt data with linux's
workaround for an imx6 chip erratum.  Linux works around the bug with
changes in fdt data that we can't currently handle, so to enable running
with standard vendor-supplied fdt data, this watches for an attempt to map
the gpio1_6 interrupt and remaps it back to the standard ethernet interrupt.

This can be undone when the intrng project is completed and our gpio drivers
can also be interrupt controllers.
Import libxo 0.1.4

Obtained from:	https://github.com/Juniper/libxo
Sponsored by:	Juniper Networks, Inc.
Add generated headers xoversion.h and xoconfig.h. These are the result
of configuring the source tree:
	% automake --add-missing
	% autoconf
	% ./configure
In all cases except CTLTYPE_STRING, penv is NULL here, so passing it
indiscriminately to printf() and freeenv() is incorrect.  Add a NULL
check before freeenv(); as for printf(), we could use req.newptr
instead, but we'd have to select the correct format string based on
the type, and that's too much work for an error message, so just
remove it.
Provide a working GPIOBUS_IVAR() macro for FDT systems.
Hook libxo to the build.

Sponsored by:	Juniper Networks, Inc.
Hook xo(1) to the build -- it's like echo, but uses libxo to
support emitting machine-readable output.

Sponsored by:	Juniper Networks, Inc.
Move the duplicated code to a single function.

No functional changes.
Three updates to PowerPC FBT:

* Use a constant to define the number of stack frames in a probe exception.
* Only allow function symbols in powerpc64 ('.' prefixed)
* Set the fbtp_roffset for return probes, so the correct dtrace_probe call is
  made.

MFC after:	1 week
Whitespace

X-MFC-with:	r273570
MFC after:	1 week
- Ignore EINVAL check with mknod(path, S_IFCHR, -1) as the testcase is always
  executed on a non-devfs filesystem
- Expect mknod(path, S_IFREG, 0) to fail on FreeBSD

Submitted by: pho
Sponsored by: EMC / Isilon Storage Division
- Test for EINVAL requirement when passing an invalid flag in to msync(2)
- Expect ENOMEM instead of EFAULT when msync'ing a previously munmap'ed region
  on FreeBSD

Submitted by: pho
Sponsored by: EMC / Isilon Storage Division
Fix formatting of vmstat (1) so that it looks cleaner on standard 80
column displays. In particular it wraps far less often.

Submitted by: Andy Kosela <akosela@andykosela.com>
PR:           191976
Merge remote-tracking branch 'freebsd/master' into hardened/current/master