enable global_header flag for audio and video encoding, was wrongly part of commit r13722
enable global_header flag for audio and video encoding, was wrongly part of commit r13722

git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@13724 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg