Don't add rF+/rC- to the autoinscriptions of randart rings of fire

(and vice versa for ice), since that's already what their base type does. Should the code ever be changed to allow them to get additional levels of resistance or susceptibility, the check is only done for the base stats (+1 and -1, respectively).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@4362 c06c8d41-db1a-0410-9941-cceddc491573

Created by  j-p-e-g  on April 19, 2008
4SI4UGBUACYU6VN6QCDV4UQJDN3WJ4IDD3B2GEVI4DGRBENQJMPQC
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