fix counting_bloom num_bytes calculation
fix counting_bloom num_bytes calculation

was trying to be a rounding-up divide by two, but wasn't

tutuhuagong/dablooms,tutuhuagong/dablooms,lenovor/dablooms,bitly/dablooms,giserh/dablooms,giserh/dablooms,tutuhuagong/dablooms,lenovor/dablooms,giserh/dablooms,ploxiln/dablooms,lenovor/dablooms,giserh/dablooms,giserh/dablooms,lenovor/dablooms,tutuhuagong/dablooms,ploxiln/dablooms,ploxiln/dablooms,bitly/dablooms,tutuhuagong/dablooms,lenovor/dablooms,giserh/dablooms,tutuhuagong/dablooms,bitly/dablooms,lenovor/dablooms