Fix uninitialized data use in MKV import. (introduced in r400)
Fix uninitialized data use in MKV import. (introduced in r400)

defaultDuration was set without being checked if it existed.


git-svn-id: d8f21eb7283bfb39ebab2f8f9b4a259b233f9348@1275 621663c8-3916-0410-8f58-edc14a8543d5

mrvacbob/perian,mrvacbob/perian,mrvacbob/perian,mrvacbob/perian,mrvacbob/perian