sharedptr_registry: remove extaneous Mutex::Locker declaration

For some reason, the lookup() retry loop (for when happened to
race with a removal and grab an invalid WeakPtr) locked
the lock again.  This causes the #3836 crash since the lock
is already locked.  It's rare since it requires a lookup between
invalidation of the WeakPtr and removal of the WeakPtr entry.

Fixes: #3836
Backport: bobtail
Signed-off-by: Samuel Just <sam.just@inktank.com>
doc: wider sidebar, larger font, cleaned tip CSS

The sidebar is now about a hundred pixels wider and the fonts
are larger throughout.  This works a lot better when you get
deep into the doc structure - it used to wrap horribly.

I also fixed how literals look inside .tip and .important.

Signed-off-by: Ross Turk <ross@inktank.com>
doc: fixed description for pg in control section.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
Merge branch 'master' of https://github.com/ceph/ceph
Merge git://github.com/ceph/ceph