Optimized remove of key when using internal cursor in BDB tables.


mysql-test/r/bdb.result:
  Test for LOCK bug
mysql-test/t/bdb.test:
  Test for LOCK bug
sql/ha_berkeley.cc:
  Fix bugs when using LOCK TABLES
  Optimized remove of key when using internal cursor
sql/ha_berkeley.h:
  Initilize of changed_rows
sql/lock.cc:
  Fix for BDB tables