Removes unused and duplicate headers.

Bring the wait limit on mailbox write to a more sane value.

Fix a off-by-one bug on wait time limit.

Remove extra blank line.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@276303 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Submitted by:	rick Maclem
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@276304 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f