Reuse connection when rebuilding boards.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@6054 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
Speed up by preventing flush.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@6055 63ad8ddf-47c3-0310-b6dd-a9e9d9715204