Dec old special inodes in inode convertROtoRW

Dec old special inodes in inode convertROtoRW

The convertROtoRW code for the inode fileserver makes copies of the
volume's special inodes, but leaves the old (RO) inodes around. If the
RO is created again, this will result in duplicate special inodes for
the same volume, which freaks out the salvager (and possibly other
things).

So IH_DEC the old RO special inodes after converting, so they go away.

Reviewed-on: http://gerrit.openafs.org/735
Tested-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit dbe3b7b8eeb4a010f82248befc6167b3b5ed9606)

Change-Id: Id545befbb38f60c262ab23b5eb5dd54439008760
Reviewed-on: http://gerrit.openafs.org/761
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>