Remove warnings from c files

Change-Id: I4c86738cb25e6951c72d6b0a351675af5104fb4f
Reviewed-on: http://review.couchbase.org/31311
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>