It was discovered that if remaining_bytes is an exact multiple of
max_payload_len in RtpPacketizerVp8::CalcNextSize, then the packetizer
will produce too many packets (i.e., split the payload into more
packets than needed).
This CL adds a test to trigger the problem.
BUG=4019
R=stefan@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/24289004
git-svn-id: http://webrtc.googlecode.com/svn/trunk@7739 4adac7df-926f-26a2-2b94-8c16560cd09d