Fix crash when LADSPA_PATH is empty string.
Fix crash when LADSPA_PATH is empty string.

j-b-m/mlt,siddharudh/mlt,wideioltd/mlt,zzhhui/mlt,anba8005/mlt,siddharudh/mlt,wideioltd/mlt,xzhavilla/mlt,siddharudh/mlt,zzhhui/mlt,j-b-m/mlt,anba8005/mlt,mltframework/mlt,wideioltd/mlt,siddharudh/mlt,mltframework/mlt,anba8005/mlt,anba8005/mlt,anba8005/mlt,siddharudh/mlt,wideioltd/mlt,j-b-m/mlt,mltframework/mlt,xzhavilla/mlt,zzhhui/mlt,wideioltd/mlt,zzhhui/mlt,mltframework/mlt,zzhhui/mlt,xzhavilla/mlt,j-b-m/mlt,j-b-m/mlt,siddharudh/mlt,wideioltd/mlt,wideioltd/mlt,xzhavilla/mlt,wideioltd/mlt,j-b-m/mlt,mltframework/mlt,mltframework/mlt,siddharudh/mlt,mltframework/mlt,siddharudh/mlt,xzhavilla/mlt,xzhavilla/mlt,zzhhui/mlt,mltframework/mlt,mltframework/mlt,mltframework/mlt,j-b-m/mlt,anba8005/mlt,xzhavilla/mlt,xzhavilla/mlt,xzhavilla/mlt,j-b-m/mlt,anba8005/mlt,anba8005/mlt,j-b-m/mlt,zzhhui/mlt,wideioltd/mlt,j-b-m/mlt,siddharudh/mlt,anba8005/mlt,zzhhui/mlt,zzhhui/mlt