qimage/producer_kdenlivetitle.c: add error handling
qimage/producer_kdenlivetitle.c: add error handling

Fixes Coverity CID 709363: Argument cannot be negative (NEGATIVE_RETURNS)
Function "ftell(f)" returns a negative number.
Assigning: signed variable "lSize" = "ftell".
 37                lSize = ftell (f);
 38                rewind (f);
 39
 40                char *infile = (char*) mlt_pool_alloc(lSize);
"lSize" is passed to a parameter that cannot be negative.

and compiler warning:

producer_kdenlivetitle.c: In function ‘read_xml’:
producer_kdenlivetitle.c:49:19: warning: ‘infile’ may be used uninitialized in this function [-Wmaybe-uninitialized]

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