Remove conditional LCB_VERSION

We don't support anything lower than 2.1.x anyway because of durability

Change-Id: Iae54aa2ecd350ee55acbcd8518b1595f1073891e
Reviewed-on: http://review.couchbase.org/29260
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>