Ticket 49476 - refactor ldbm backend to allow replacement of BDB
BACKEND REDESIGN -Phase 1
This patch provides the first phase of the backend redesign. It does
split the configuration of the LDBM layer and the DB specific layer.
The dblayer_private defines a set of functions to be used by the LDBM
layer and to be implemented by the DB layer.
Currently this is only done for the BDB implementation, the patch automatically
splits the configuration for existing instances