Add patch: Do not forward declare WebRtcVoiceChannelInfo.

This seems to be necessary to compile for OSX 10.7,
and this is the OSX version we currently use in the CI system.

Change-Id: I2363b48b66cd7fda603ff9783934ca44c1656723
Reviewed-by: Andras Becsi <andras.becsi@digia.com>
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>