Fix check for monsters' negative energy resistance with regard to

draining attacks.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8553 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on January 18, 2009
O6H3XJJQQBOGTFEBWU7UBLBF5F7JWCHS2HRGA6FA6EXGSXZQZVOQC
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