Use second version of the lcb_create_st in C++ constructor

Change-Id: I5dde502fffe74fb97718b35877e27da80d5f4fb3
Reviewed-on: http://review.couchbase.org/30864
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>