Updated sparse warning message patches

[Alex Elder <elder@inktank.com>]

I'm re-posting these patches because I've updated them to be
based on the patches I just posted ("Four miscellaneous patches").

These patches are available in the branch "test/wip-4184" in
the ceph-client git repository.  That branch is based on
branch "test/wip-4234,5,7,8".

(Here's the original description)

What follows is a few series of patches that get rid of code
issues that lead to warnings from the sparse utility.

The first three patches address the warnings in the rbd, ceph
file system, and libceph code respectively.  After that, one
warning remains in libceph, and that is addressed by a series
of five patches which both address the underlying problem and
reorganized and clean up the surrounding code.  The last two
are meant to be combined into one before commit; they've been
posted as two separate patches to make them easier to review.

					-Alex

[PATCH, v2] rbd: eliminate sparse warnings
[PATCH, v2] ceph: eliminate sparse warnings in fs code
[PATCH, v2] libceph: eliminate sparse warnings
[PATCH 1/5, v2] libceph: encapsulate connection backoff
[PATCH 2/5, v2] libceph: separate non-locked fault handling
[PATCH 3/5, v2] libceph: use a flag to indicate a fault has occurred
[PATCH 4/5, v2] libceph: use a do..while loop in con_work()
[PATCH 5/5, v2] libceph: indent properly