extras/ios: remove dropped configure options from build script and disable audioqueue aout
extras/macosx: remove dropped options from configure script
transcode: add more channels on audio

Assume that 3 channels is 2.1 instead of 3 front channels,
also 6 is 5.1.

Ref #1897
avcodec:multichannel encoding support

Make some assumptions on channels, like 6 channels is 5.1 etc.

Ref #1897
audioqueue: fix compilation when enabled with --enable-audioqueue