MFC r318820:
Increase the allowed maximum number of audio channels from 31 to 127
in the PCM feeder mixer. Without this change a value of 32 channels is
treated like zero, due to using a mask of 0x1f, causing a kernel
assert when trying to playback bitperfect 32-channel audio. Also
update the AWK script which is generating the division tables to
handle more than 18 channels. This commit complements r282650.