MFC 253887,253977:

- Use pget(PGET_CANDEBUG | PGET_NOTWEXIT) to determine if the specified
  PID is valid for monitoring in FILEMON_SET_PID ioctl.

- Set the monitored PID to -1 when the process exits.

Suggested by:	jilles
Tested by:	sjg
Clearing the rxbuf flags got lost along the way... adding it back.
Synchronize stable/9 Forth code with head via MFC of 22 revisions:
227727, 233941, 235560, 238431, 241310, 241361, 241363, 241365, 241367,
241523, 242667-242669, 242923, 243114, 243660, 244048, 244089, 244158,
253715, 254105, and 254108.

This includes critical fixes that sadly should have been merged prior.
Namely, SVN r244158 fixes a possible regression.
MFC 235964,236311,247505
	Add the INET opt file creation, module name change, and include
	making the Makefile match HEAD.
MFC r253527:
Move the convert_sigevent32() utility function into freebsd32_misc.c
for consumption outside the vfs_aio.c.

For SIGEV_THREAD_ID and SIGEV_SIGNAL notification delivery methods,
also copy in the sigev_value, since librt event pumping loop compares
note generation number with the value passed through sigev_value.
MFC r253528:
The freebsd32_lio_listio() compat syscall takes the struct sigevent32.
Regenerate.
MFC r253529:
Wrap kmq_notify(2) for compat32 to properly consume struct sigevent32
argument.
Regenerate.
MFC r253530:
Implement compat32 wrappers for the ktimer_* syscalls.
Regenerate.
MFC alignment fix for libcxxrt.
releng/9.2 was branched, so call this -PRERELEASE again for the duration
of the 9.2-RELEASE cycle.
MFC r242688: Hook in new files menusets.4th and manual.
MFC	r253173:

Implement 1003.1-2001 pathconf() keys.
This is based on r106058 in UFS.
MFC	r252435, r252437, r253163:
Change i_gen in UFS to an unsigned type.

In UFS, i_gen is a random generated value and there is not way for
it to be negative. Actually, the value of i_gen is just used to
match bit patterns and it is of no consequence if the values are
signed or not. Following other filesystems, set it to unsigned,

Calculation for older filesystems remains untouched.
MFC: 254004

As it turns out, MSIs are broken with 2820SA so introduce an AAC_FLAGS_NOMSI
quirk and apply it to these controllers [1]. The same problem was reported
for 2230S, in which case it wasn't actually clear whether the culprit is the
controller or the mainboard, though. In order to be on the safe side, flag
MSIs as being broken with the latter type of controller as well. Given that
these are the only reports of MSI-related breakage with aac(4) so far and
OSes like OpenSolaris unconditionally employ MSIs for all adapters of this
family, however, it doesn't seem warranted to generally disable the use of
MSIs in aac(4).
While at it, simplify the MSI allocation logic a bit; there's no need to
check for the presence of the MSI capability on our own as pci_alloc_msi(9)
will just fail when these kind of interrupts are not available.
Reported and tested by: David Boyd [1]
MFC: r253266

Prefix the alias macros for members of struct __mcontext with an underscore
in order to avoid a clash in the net80211 code.
MFC: r253742

- Add const-qualifiers to the arguments of isonum_*().
- According to ISO 9660 7.1.2, isonum_712() should return a signed value.
- Try to get isonum_*() closer to style(9).
MFC: r253899, r253920

- Implement iclear methods for QUICC and SAB 82532. With r253161 in place,
  this is is crucial at least for the latter.
  What happens is that attaching uart(4) to scc(4) causes the SAB 82532 to
  "receive" something and trigger a SER_INT_RXREADY interrupt, given that
  at least fast/filter interrupts are already enabled. Prior to r253161,
  uart_bus_ihand() was set up at this point and handled that condition,
  i. e. read the RX FIFO and issued a Receive Message Complete.
  Now, uart_bus_ihand() and uart_intr() are setup after attaching uart(4),
  leaving the SER_INT_RXREADY interrupt triggered during the latter to
  be handled by the iclear method. However, with that method not implement,
  this in turn causes SAB 82532 to not issue any further SER_INT_RXREADY
  interrupts until the RX FIFO is full again. Thus, 15 received bytes go
  to nowhere, given that "the other half" of the RX FIFO is used for status
  information. Hence, implementing sab82532_bfe_iclear() fixes things again.
  Potentially, the same problem exists for QUICC.
- Remove unnecessary __RMAN_RESOURCE_VISIBLE.
- Remove a superfluous header.
- Use KOBJMETHOD_END.
- Mark unused arguments as such.
- Remove variables unused after initialization.

Reviewed by:	marcel (earlier version)