Fix divide by zero in mlt_filter_get_progress().
Fix divide by zero in mlt_filter_get_progress().

mltframework/mlt,mltframework/mlt,mltframework/mlt,siddharudh/mlt,siddharudh/mlt,siddharudh/mlt,j-b-m/mlt,mltframework/mlt,j-b-m/mlt,j-b-m/mlt,xzhavilla/mlt,j-b-m/mlt,mltframework/mlt,xzhavilla/mlt,j-b-m/mlt,j-b-m/mlt,mltframework/mlt,siddharudh/mlt,j-b-m/mlt,siddharudh/mlt,j-b-m/mlt,j-b-m/mlt,mltframework/mlt,xzhavilla/mlt,mltframework/mlt,xzhavilla/mlt,siddharudh/mlt,siddharudh/mlt,mltframework/mlt,xzhavilla/mlt,xzhavilla/mlt,mltframework/mlt,xzhavilla/mlt,siddharudh/mlt,xzhavilla/mlt,j-b-m/mlt,siddharudh/mlt,xzhavilla/mlt