Fix bug #2512419: game crashing when there isn't any room to place god-sent

monsters.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8493 c06c8d41-db1a-0410-9941-cceddc491573

Created by  zelgadis  on January 16, 2009
56EWIFLWBAYE3XY6VJGMEOYWBKP73FY6G74BGWXPAEZPFFHTLLTQC
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