MFC r294933,r294949,r294952,r294953,r294957,r294965,r294967,r294968,r295017,

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)

git-svn-id: svn://svn.freebsd.org/base/stable/10@296015 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f