Adjust dolinks.sh so that it can be run more than once without

generating warnings or dangling symlinks.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@3202 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on January 5, 2008
5DSMXTTFTRSIWK43IEDZ3L4253JK7JXIFIMMH3AXCTM7IPTGHBTAC
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