This CL handles frame rotation by updating the OpenGL vertex data in
RTCOpenGLVideoRenderer, instead of calling the expensive
libyuv::I420Rotate that will rotate the actual memory. Also, we can
handle rotated native frames instead of falling back to
NativeToI420Buffer.
Review-Url: https://codereview.webrtc.org/2176623002
Cr-Commit-Position: refs/heads/master@{#13715}
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