Remove unused RtpStatistics struct.
Remove unused RtpStatistics struct.

This unused struct is basically a copy of RtcpStatistics in
webrtc/common_types.h. I expect this wasn't properly removed when that
one was added.

R=tommi@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/25239004

git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@7758 4adac7df-926f-26a2-2b94-8c16560cd09d

mwgoldsmith/libilbc,mwgoldsmith/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc,mwgoldsmith/ilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,mwgoldsmith/ilbc