Clean up the non-stacking of Zin's divine boosts and the equivalent

mutations.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@5055 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on May 15, 2008
76LKB66IWIPTE75HR2T4B75YFRVZ3PVRPX5WTRPNTOOP3SLAQWFAC
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