Add flags for formatting c code with astyle

Change-Id: I0fa429d7883463e420de1f849657a9284b172b3c
Reviewed-on: http://review.couchbase.org/28760
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>