Port autofs to DragonFly

[Tomohiro Kusumi]

autofs has been pushed to master.
https://gitweb.dragonflybsd.org/dragonfly.git/commit/e2950f411cf734644d0586c7ed409af918988d76

2016-06-03 1:40 GMT+09:00 Tomohiro Kusumi <kusumi.tomohiro at gmail.com>:
> The VFS change I made (which is kinda sensitive one) was accepted by Matt,
> so I'll be committing autofs to master in a few days.
>
>
> 2016-05-26 10:17 GMT+09:00 Tomohiro Kusumi <kusumi.tomohiro at gmail.com>:
>> The code has been tested by a user.
>> A simple configuration works without issues just like it did on my machines.
>>
>> If it works the same with more complex configurations the user
>> normally uses, and if one VFS change I made to nlookup() (which
>> doesn't affect or used by other filesystems) is acceptable by Matt,
>> I'd like autofs to go into master for upcoming 4.6.
>>
>> I'll make the code without bunch of debug kprintfs available hopefully
>> in a few days.