Correct my previous commit:

- getrusage_utime_back succeeds reliably on FreeBSD
- getrusage_utime_zero passes/fails in a seemingly non-deterministic manner.
  Skip it for now (and fix it later)

In the initial port of this testcase to FreeBSD, the results failed reliably
in the same manner as it does on NetBSD

Sponsored by: EMC / Isilon Storage Division
- Add sys/types.h for the APIs in sys/sysctl.h
- Poke at VM_MIN_ADDRESS in machine/vmparam.h because FreeBSD doesn't have a
  vm.minaddress sysctl analog
- Expect ENOMEM instead of EAGAIN in mlock_limits
- Provide mlock an mmap'ed page twice to simulate MAP_WIRED on NetBSD

In collaboration with: pho
Sponsored by: EMC / Isilon Storage Division
Update the network interface baudrate integer according to the actual
line rate.

Submitted by:	jhb @
MFC after:	1 week
Fix documentation issue.

PR:		194581
Submitted by:	madpilot
HPET: create /dev/hpetN as a way to access HPET from userland.

In some cases, TSC is broken and special applications might benefit
from memory mapping HPET and reading the registers to count time.
Most often the main HPET counter is 32-bit only[1], so this only gives
the application a 300 second window based on the default HPET
interval.
Other applications, such as Intel's DPDK, expect /dev/hpet to be
present and use it to count time as well.

Although we have an almost userland version of gettimeofday() which
uses rdtsc in userland, it's not always possible to use it, depending
on how broken the multi-socket hardware is.

Install the acpi_hpet.h so that applications can use the HPET register
definitions.

[1] I haven't found a system where HPET's main counter uses more than
32 bit.  There seems to be a discrepancy in the Intel documentation
(claiming it's a 64-bit counter) and the actual implementation (a
32-bit counter in a 64-bit memory area).

MFC after:	1 week
Relnotes:	yes
Fix a bug where DMA maps created with bus_dmamap_create() won't increment
the map count and without being able to keep track of the current map
allocation, bus_dma_tag_destroy() will fail to proceed and will return
EBUSY even after all the maps have been correctly destroyed with
bus_dmamap_destroy().

Found while testing the detach method of a NIC.

Tested on:	BBB (am335x)
Reviewed by:	cognet, ian
MFC after:	1 week
Don't reference sem(4) from the POSIX semaphore pages.  POSIX semaphores
were reimplemented using umtx in FreeBSD 9 and no longer use sem(4).
HPET: avoid handling the multiple file-descriptor case.

It had two bugs: one where mmap was still allowed and another where
D_TRACKCLOSE doesn't handle all cases.

Thanks to jhb and kib for pointing them out.
MFC after:	1 week
Add COMPAT_FREEBSD9 and COMPAT_FREEBSD10 options to wrap code that
provides compatability for FreeBSD 9.x and 10.x binaries.  Enable
these options in kernel configs that enable other COMPAT_FREEBSD<n>
options.
The current POSIX semaphore implementation stores the _has_waiters flag
in a separate word from the _count.  This does not permit both items to
be updated atomically in a portable manner.  As a result, sem_post()
must always perform a system call to safely clear _has_waiters.

This change removes the _has_waiters field and instead uses the high bit
of _count as the _has_waiters flag.  A new umtx object type (_usem2) and
two new umtx operations are added (SEM_WAIT2 and SEM_WAKE2) to implement
these semantics.  The older operations are still supported under the
COMPAT_FREEBSD9/10 options.  The POSIX semaphore API in libc has
been updated to use the new implementation.  Note that the new
implementation is not compatible with the previous implementation.
However, this only affects static binaries (which cannot be helped by
symbol versioning).  Binaries using a dynamic libc will continue to work
fine.  SEM_MAGIC has been bumped so that mismatched binaries will error
rather than corrupting a shared semaphore.  In addition, a padding field
has been added to sem_t so that it remains the same size.

Differential Revision:	https://reviews.freebsd.org/D961
Reported by:	adrian
Reviewed by:	kib, jilles (earlier version)
Sponsored by:	Norse
Eliminate conf_lock and instead rely on the NSS write lock to protect
NSS configuration state.

As a side effect, this fixes a race condition which can occur if multiple
threads call nsdispatch(3) concurrently before nsswitch.conf has been
parsed. Previously, the thread holding conf_lock could cause other threads
to return from nss_configure() before nsswitch.conf had been parsed, forcing
them to fall back to the default sources for their NSS methods.

Reviewed by:		jhb
Differential Revision:	https://reviews.freebsd.org/D994
MFC after:		1 month
Sponsored by:		EMC / Isilon Storage Division
Fix cpsw_detach() to not panic when called from cpsw_attach().

For an unkown reason (at moment), sometimes if_cpsw cannot read from PHY
and fails to attach calling cpsw_detach() which end up in a panic.

Fix it by doing the proper check before detach the miibus and also fix the
leak of few variables.

And to actually make it work, ether_ifattach() has to be moved to the end
of cpsw_attach() to avoid a race where calling ether_ifdetach() before
domain_init() (which will only run later on) would make it crash at
INP_INFO_RLOCK() on in_pcbpurgeif0().

Tested on:	BBB (am335x)
MFC after:	1 week
Add a sysctl to control the HPET allow_write behaviour.

Requested by:	kib