Close the Berkeley DB environment, freeing any allocated resources and closing
any underlying subsystems.
This does not imply closing any databases that were opened in the
environment.
Where the environment was initialized with the -lock option,
calling envclose does not release any locks still held by the
closing process, providing functionality for long-lived locks.
Once envclose has been called the env handle may not be
accessed again.
The envclose command returns 0 on success, and in the case of error, a Tcl error
is thrown.