aufs: bugfix, missing mnt_want_write in moo

In move-up-on-open, between copying-up to the upper branch and unlinking
on the lower branch, mnt_want_write is necessary.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
aufs: tiny, move defs to uapi header

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
aufs: new ioctl BRINFO

AUFS_CTL_BRINFO returns the information about all branches.
The information is equivalent to the entries under sysfs/fs/aufs, but
this interface is atomic and never confuses the matching of the branch
id.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Merge remote-tracking branch 'aufs3-standalone/aufs3.9/00base' into aufs3.9/10static
Merge branch 'aufs3.9/10static' into aufs3.9/11proc_map
Merge branch 'aufs3.9/11proc_map' into aufs3.9/18public
aufs: bugfix, restore the lost unlock in an error path

A call to au_unpin() in an error path was lost by an old commit
	fb3f6aa 2013-04-21 Merge branch 'aufs3.5/00base' into aufs3.6/00base
which got conflicts in git-merge and I fixed them manually.
In this manual fix I made a mistake and A call to au_unpin() in an error
path was lost.
It means the last version of aufs3.6 - aufs3.8 has this bug and not
fixed because they are not maintained now.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Merge remote-tracking branch 'aufs3-standalone/aufs3.9/00base' into aufs3.9/10static
Merge branch 'aufs3.9/10static' into aufs3.9/11proc_map
Merge branch 'aufs3.9/11proc_map' into aufs3.9/18public