This isn't necessary here, and for some reason broke only multichannel AAC encoding when a channel layout tag was set.
Fixes error "libavcodec/audiotoolboxenc.c:294:50: error: use of undeclared identifier 'kAudioCodecPropertyPacketSizeLimitForVBR'." That was added to 10.9: https://developer.apple.com/library/mac/releasenotes/General/APIDiffsMacOSX10_9/AudioUnit.html Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Fixes trac #4828