Update databases/libzdb to version 3.2.3.

Pkgsrc changes:
* More patching of isxxxx() uses to u_char.

Upstream changes:

Version 3.2.3
-------------
* New: Provide better error reporting if a Connection cannot be
  obtained from the Connection Pool by introducing the method
  ConnectionPool_getConnectionOrException(). In C++ the exception
  thrown now contains the actual cause instead of a generic error.
* Fix: In C++ guard against stopping the Connection Pool with active
  Connections. I.e. all Connections should be returned to the pool
  before explicitly attempting to stop the pool. This is due to how
  C++ destructors are called at scope end; if there is a reference
  to a live Connection object after the pool is stopped it might cause
  a dealloc sequence problem.
* Fix: Issue #50 where unit test 5 could fail for MariaDB because
  mysql_stmt_affected_rows() only returns actual affected rows, not
  matched rows which MySQL does.
* Fix: plus other minor improvements and fixes

(he)