MFC r294933,r294949,r294952,r294953,r294957,r294965,r294967,r294968,r295017,
r295026,r295027,r295029,r295030,r295649:

r294933:
Drop any previous fd when setting a new one.
r294949:
filemon_ioctl: Handle error from devfs_get_cdevpriv(9).
r294952:
filemon_ioctl: Lock the associated filemon handle before writing to it.
r294953:
filemon_comment has nothing to do with wrappers so move it out of
filemon_wrapper.c.
r294957:
filemon_dtr: Lock the associated filemon handle before writing to it.
r294965:
filemon: Use process_exit EVENTHANDLER to capture process exit.
r294967:
filemon: Trace fork via process_fork event.
r294968:
Follow-up r294967: Mark flags unused.
r295017:
filemon: Use process_exec EVENTHANDLER to capture sys_execve.
r295026:
filemon_open: Don't record a process to trace here.
r295027:
filemon: Track the process pointer rather than a pid.
r295029:
Document the purpose and non-purpose of filemon(4).
r295030:
Note the double fork behavior with filemon.
r295649:
filemon: Fix panic when fork1() is called from kproc_create().

Approved by: re (marius)

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Match the options of the kernel.

Finish migration of MAINTAINER entries

Approved by: cperciva
MFC after: 3 days

Add the 'filemon' device. 'filemon' is a kernel module that provides a device
interface for processes to record system calls of its children.

Submitted by: Juniper Networks.