CBIDXT-136 Handle break properly in Slice Writer

A "break" statement terminates execution of the
innermost "for", "switch" or "select" statement.

Change-Id: Id71b5dcdde0234da9e78932c8f203cb1ebc2c199
Reviewed-on: http://review.couchbase.org/41017
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>