Fixed compile error (ftruncate wants unistd.h, which is not already included for

DOS and Windows).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@1912 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dshaligram  on July 22, 2007
YED35BDFAUH7W5Q4YCXV4442GO6LYMWQ2YUPO2UYKG4M55Q2ALIQC
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