OSD: allow project_pg_history to handle a missing map

If we get a peering message for an old map we don't have, we
can throwit out: the sending OSD will learn about the newer
maps and update itself accordingly, and we don't have the
information to know if the message is valid. This situation
can only happen if the sender was down for a long enough time
to create a map gap and its PGs have not yet advanced from
their boot-up maps to the current ones, so we can rely on it

Fixes: #6712
Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
(cherry picked from commit cd0d612e1abdf5c87082eeeccd4ca09dd14fd737)
init, upstart: prevent daemons being started by both

There can be only one init system starting a daemon. If there is a
host entry in ceph.conf for a daemon, sysvinit would try to start it
even if the daemon's directory did not include a sysvinit file. This
preserves backwards compatibility with older installs using sysvinit,
but if an upstart file is present in the daemon's directory, upstart
will try to start them, regardless of host entries in ceph.conf.

If there's an upstart file in a daemon's directory and a host entry
for that daemon in ceph.conf, both sysvinit and upstart would attempt
to manage it.

Fix this by only starting daemons if the marker file for the other
init system is not present. This maintains backwards compatibility
with older installs using neither sysvinit or upstart marker files,
and does not break any valid configurations. The only configuration
that would break is one with both sysvinit and upstart files present
for the same daemon.

Backport: emperor, dumpling
Reported-by: Tim Spriggs <tims@uahirise.org>
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
(cherry picked from commit 5e34beb61b3f5a1ed4afd8ee2fe976de40f95ace)