codec2: add C2SoftVpx

Test: setprop debug.stagefright.ccodec true
Test: stagefright -S -N c2.google.vp8.decoder /sdcard/clips/bbb_vp8.webm
Test: stagefright -S -N c2.google.vp9.decoder /sdcard/clips/bbb_vp9.webm

Change-Id: Ib7ddecd43191f1129577a84841f25bb4940f377d
3 files changed