Log Message:
Update py-bsddb3 to 4.2.4.

Changes:
 * changed DB and DBEnv set_get_returns_none() default from 1 to 2.
 * cleaned up compatibility iterator interface.
 * the legacy compatibility dict-like interface now support iterators
   and generators and allows multithreaded access to the database.
 * fixed a tuple memory leak when raising "object has been closed"
   exceptions for DB, DBEnv and DBCursor objects.  I doubt much
   previous code triggered this.
 * use of a closed DBCursor now raises a DBCursorClosedError exception
   subclass of DBError rather than a boring old DBError.
 * added DBCursor.get_current_size() method to return the length in bytes
   of the value pointed to by the cursor without reading the actual data.
 * Standalone pybsddb builds now use a _pybsddb dynamic/shared library
   rather than _bsddb.  This allows for pybsddb to be built, installed
   and used on python >= 2.3 which includes an older version of pybsddb
   as its bsddb library.
 * Can now compile and link with BerkeleyDB 4.2.x (when its released).
 * the legacy bsddb module supports the iterator interface on python 2.3.
 * Support the DBEnv.set_shm_key() method.
 * Fixed setup.py include/{db4,db3} header file searching (SF bug #789740).