red: fix SendCodecSpec == operator

The == operator needs to take the red_payload_type into account as
well.

BUG=webrtc:11640

Change-Id: Iae285643f60ca92704d17c0c088d8fb4b3cdc180
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/178815
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31869}

call/audio_send_stream.cc

@@ -88,6 +88,7 @@ bool AudioSendStream::Config::SendCodecSpec::operator==(
   if (nack_enabled == rhs.nack_enabled &&
       transport_cc_enabled == rhs.transport_cc_enabled &&
       cng_payload_type == rhs.cng_payload_type &&
+      red_payload_type == rhs.red_payload_type &&
       payload_type == rhs.payload_type && format == rhs.format &&
       target_bitrate_bps == rhs.target_bitrate_bps) {
     return true;