[2000669] Fixing logic error that may have caused untargetable resting monsters to be created. If place_monster was called with force_pos, it could create monsters on top of other monsters. If that monster was resting (and thus never moved) and the first monster did move, the first monster would set mgrd to NON_MONSTER, making the resting monster untargetable.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@6411 c06c8d41-db1a-0410-9941-cceddc491573

Created by  ennewalker  on July 5, 2008
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