CCodec: do not assume exactly one buffer per worklet

Bug: 72419260
Test: setprop debug.stagefright.ccodec yes
Test: stagefright -S -N c2.google.avc.decoder /sdcard/a.mp4
Test: stagefright -ao -N c2.google.aac.decoder /sdcard/a.mp4
Test: audioloop -N c2.google.aac.encoder -M audio/mp4a-latm
Test: screenrecord --codec-name c2.google.avc.encoder /sdcard/record.mp4
Change-Id: Ifb5deecc31faf9f1d550b454998edd0ea25364aa