osdc/Objecter: resend ops in the last_force_op_resend epoch

If we are a client, and process a map that sets last_force_op_resend to
the current epoch, force a resend of this op.

If the OSD expects us to do this, it will discard our previous op.  If the
OSD is old, it will process the old one, this will appear as a dup, and we
are no worse off than before.

Signed-off-by: Sage Weil <sage@inktank.com>
osd: discard client ops sent before last_force_op_resend

If an op is sent before last_force_op_resend, and the client's feature is
present, drop the op because we know they will resend.

Signed-off-by: Sage Weil <sage@inktank.com>
mon/OSDMonitor: force op resend when pool overlay changes

If a client is sending a sequence of ops (say, a, b, c, d) and partway
through that sequence it receives an OSDMap update that changes the
overlay, the ops will get send to different pools, and the replies will
come back completely out of order.

To fix this, force a resend of all outstanding ops any time the overlay
changes.

Fixes: #8305
Signed-off-by: Sage Weil <sage@inktank.com>