librados: unconditionally pass WATCH_NOTIFY to legacy callback

This was always WATCH_NOTIFY; just pass that explicitly.  No need to
pay attention to what's in the message.

Signed-off-by: Sage Weil <sage@redhat.com>
osd: assume WATCH_NOTIFY for MWatchNotify

Signed-off-by: Sage Weil <sage@redhat.com>
librados: define CEPH_OSD_WATCH_OP_*

Signed-off-by: Sage Weil <sage@redhat.com>
librados: use new watch op codes; simplify Objecter helpers

- drop the useless add_watch() helper; do it explicitly
- drop the unused var arg everywhere
- make a separate notify member of the union that excludes
  the other unused fields

Signed-off-by: Sage Weil <sage@redhat.com>
osdc/Objecter: fix assert_src_version

Don't use the add_watch() helper; do it like assert_version
does it.

Signed-off-by: Sage Weil <sage@redhat.com>
squashme: add reconnect op
wip