mkvparser: Avoid double free when Chromaticity parse fails.

PrimaryChromaticity::Parse never owns the PrimaryChromaticity
it allocates-- avoid freeing it because doing so results in a
double free when the MasteringMetadata dtor runs.

BUG=webm:1381

Change-Id: Ief0159f6ab667234e3fdc51c65f23ef5efb32a71
1 file changed