[exp] Fix histogram_mr.sh

exp/run.d/histogram_mr.sh

@@ -10,7 +10,7 @@ prepare_histogram_mr() {
     fi
 }
 
-dump_volrend() {
+dump_histogram_mr() {
     sha1sum $HISTOGRAM_MR_BIN              >>$dump_program_dir/histogram_mr
     sha1sum $HISTOGRAM_MR_INPUTS_DIR/input >>$dump_program_dir/histogram_mr
 }