Fix an out of bounds read in the test harness when testing
DVBContentIdentifierDescriptor. The length value inside the
data block was longer than the data block itself, thus leading
to the DVBContentIdentifierDescriptor code reading off the
end of the array.

This is the cause of the occasional unit test failures on
some of the buildslaves, due to the test harness segfaulting.

Thanks to dekarl for the tweak to the data.