cmake: remove redundant checks around CMAKE_{AR,RANLIB}
cmake: remove redundant checks around CMAKE_{AR,RANLIB}

Those are always set, no point in checking. #1065

eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero