Silence some more annoying Clang warnings

Such as -Wcast-align from char to other types

Change-Id: Ic670529c170c096ce33e33ffbfb32eff77a520c1
Reviewed-on: http://review.couchbase.org/37783
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>