fix roundoff problem in float-counts-prune.cc by adding double precision variable
fix roundoff problem in float-counts-prune.cc by adding double precision variable

chris920820/pocolm,wantee/pocolm,keli78/pocolm,wantee/pocolm,wantee/pocolm,chris920820/pocolm,keli78/pocolm,chris920820/pocolm,keli78/pocolm,wantee/pocolm,keli78/pocolm,chris920820/pocolm