MFC r253859:
Remove unused malloc type.
MFC r253187:
Do not invalidate page of the B_NOCACHE buffer or buffer after an I/O
error if any user wired mappings exist.
MFC r253188:
In the vm_page_set_invalid() function, do not assert that the page is
not busy, since its only caller brelse() can legitimately call it on
busy page.
MFC r253189:
Never remove user-wired pages from an object when doing
msync(MS_INVALIDATE).  The vm_fault_copy_entry() requires that object
range which corresponds to the user-wired vm_map_entry, is always
fully populated.

Add OBJPR_NOTWIRED flag for vm_object_page_remove() to request the
preserving behaviour, use it when calling vm_object_page_remove() from
vm_object_sync().
MFC r253190:
Add the thread owner of the MAP_ENTRY_IN_TRANSITION flag to struct
vm_map_entry.  In vm_map_wire() and vm_map_unwire(), only process the
entries which transition owner is the current thread.
MFC r253191:
The vm_fault() should not be allowed to proceed on the map entry which
is being wired now.  The entry wired count is changed to non-zero in
advance, before the map lock is dropped.  This makes the vm_fault() to
perceive the entry as wired, and breaks the fragment which moves the
wire count from the shadowed page, to the upper page, making the code
unwiring non-wired page.

On the other hand, the vm_fault() calls from vm_fault_wire() should be
allowed to proceed, so only drain MAP_ENTRY_IN_TRANSITION from
vm_fault() when wiring_thread is not current.
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.
Merge remote-tracking branch 'upstream-github/stable/9' into stable/9