Integration into ./configure ( --enable-bdb2 ).
Adaptation of the test-suite ( 'make' -> ldbm; 'make bdb2-local' -> bdb2 ).
Minor fixes in slapd/libldbm.
BEWARE: the backend will be compiled.
the backend will NOT be invoked, yet.
the backend CANNOT be invoked, yet, because it is NOT yet
integrated into the new initialization/startup environment
of the slapd server.