codec2: add C2SoftG711

Test: setprop debug.stagefright.ccodec true
Test: stagefright -ao -N c2.google.g711.alaw.decoder /sdcard/clips/alaw.wav
Test: stagefright -ao -N c2.google.g711.mlaw.decoder /sdcard/clips/mlaw.wav

Change-Id: Ie360a42bc246b94a8594a8ffd3335ac8e72f12c3
4 files changed