change switch statements to return instead of assert fixing warning on missing break.
BUG=none
TEST=none
Review URL: https://webrtc-codereview.appspot.com/382004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@164 16f28f9a-4ce2-e073-06de-1de4eb20be90
3 files changed