libceph: update ceph_msg_header structure
libceph: update ceph_msg_header structure

2 bytes of what was reserved space is now used by userspace for the
compat_version field.

Signed-off-by: John Spray <a0ab4ec42db5a70bbcbfc74d8971c0305528d92b@redhat.com>
Reviewed-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs