Include errno.h to fix DOS compile.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@785 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dshaligram  on January 4, 2007
SVVWWP2OEIFBRQHB3QHVRCCJ2ASNZ4JEYRABJZXZSYR3NAEPRLRAC
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