messages/MMonProbe: fix uninitialized variables

Backport: cuttlefish
Signed-off-by: Sage Weil <sage@inktank.com>
messages/MMonHealth: remove unused flag field

This was initialized in (one of) the ctor(s), but not encoded/decoded,
and not used.  Remove it.  This makes valgrind a happy.

Signed-off-by: Sage Weil <sage@inktank.com>
mon: fix leak of loopback Connection

The accessor returns a reference.  Instead of taking+dropping it each
time, take one ref in Monitor ctor and release it in the dtor.

Signed-off-by: Sage Weil <sage@inktank.com>
Merge remote-tracking branch 'gh/next-leaks' into next

Reviewed-by: Joao Eduardo Luis <joao.luis@inktank.com>