ocfs2: Pack vote message and response structures

The ocfs2_vote_msg and ocfs2_response_msg structs needed to be
packed to ensure similar sizeofs in 32-bit and 64-bit arches. Without this,
we had inadvertantly broken 32/64 bit cross mounts.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>