Fix memory leak in colo-compare.c and filter-rewriter.c
Report by Coverity and add some comments.
Signed-off-by: NZhang Chen <zhangchen.fnst@cn.fujitsu.com>
Reviewed-by: Nzhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>