Apply the H.264 packetization patch

Get the patch from
https://bug985254.bugzilla.mozilla.org/attachment.cgi?id=8410454 and
apply it to this branch
Merge branch 'screen_gmp' of https://github.com/ruil2/gecko-dev into screen_gmp
Merge branch 'screen_gmp' of https://github.com/ruil2/gecko-dev into screen_gmp
Hard code to enable H.264 packetization