Fix the comparison between unsigned and negative
Fix the comparison between unsigned and negative

REBFLG is defined as unsigned, so "ccr < 0" is always false. However,
this function seems not to be really executed anywhere.

Found by coverity.

draegtun/ren-c,codebybrett/ren-c,draegtun/ren-c,rgchris/ren-c,rgchris/ren-c,draegtun/ren-c,kealist/ren-c,hostilefork/rebol,giuliolunati/ren-c,hostilefork/rebol,draegtun/ren-c,giuliolunati/ren-c,rgchris/ren-c,kealist/ren-c,giuliolunati/ren-c,draegtun/ren-c,mbk/ren-c,mbk/ren-c,kealist/ren-c,codebybrett/ren-c,hostilefork/rebol,hostilefork/rebol,giuliolunati/ren-c,hostilefork/rebol,giuliolunati/ren-c,rgchris/ren-c,codebybrett/ren-c,kealist/ren-c,draegtun/ren-c,rgchris/ren-c,codebybrett/ren-c,mbk/ren-c,codebybrett/ren-c,hostilefork/rebol,kealist/ren-c,mbk/ren-c,kealist/ren-c,codebybrett/ren-c