Revert "Implement H264 simulcast support and generalize SimulcastEncoderAdapter use for H264 & VP8."

This reverts commit 07efe436c9002e139845f62486e3ee4e29f0d85b.

Reason for revert: Breaks downstream project.

cricket::GetSimulcastConfig method signature has been updated.
I think you can get away with a default value for temporal_layers_supported (and then you can remove it after a few days when projects will be updated).


Original change's description:
> Implement H264 simulcast support and generalize SimulcastEncoderAdapter use for H264 & VP8.
> 
> * Move SimulcastEncoderAdapter out under modules/video_coding
> * Move SimulcastRateAllocator back out to modules/video_coding/utility
> * Move TemporalLayers and ScreenshareLayers to modules/video_coding/utility
> * Move any VP8 specific code - such as temporal layer bitrate budgeting -
>   under codec type dependent conditionals.
> * Plumb the simulcast index for H264 in the codec specific and RTP format data structures.
> 
> Bug: webrtc:5840
> Change-Id: Ieced8a00e38f273c1a6cfd0f5431a87d07b8f44e
> Reviewed-on: https://webrtc-review.googlesource.com/64100
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Stefan Holmer <stefan@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#23705}

TBR=sprang@webrtc.org,stefan@webrtc.org,mflodman@webrtc.org,hta@webrtc.org,sergio.garcia.murillo@gmail.com,titovartem@webrtc.org,agouaillard@gmail.com

Change-Id: Ic9d3b1eeaf195bb5ec2063954421f5e77866d663
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:5840
Reviewed-on: https://webrtc-review.googlesource.com/84760
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23710}
diff --git a/modules/video_coding/include/video_codec_interface.h b/modules/video_coding/include/video_codec_interface.h
index d5c4223..1b5e155 100644
--- a/modules/video_coding/include/video_codec_interface.h
+++ b/modules/video_coding/include/video_codec_interface.h
@@ -70,7 +70,6 @@
 
 struct CodecSpecificInfoH264 {
   H264PacketizationMode packetization_mode;
-  uint8_t simulcast_idx;
 };
 
 union CodecSpecificInfoUnion {
@@ -84,9 +83,7 @@
 // must be fitted with a copy-constructor. This is because it is copied
 // in the copy-constructor of VCMEncodedFrame.
 struct CodecSpecificInfo {
-  CodecSpecificInfo() : codecType(kVideoCodecUnknown), codec_name(nullptr) {
-    memset(&codecSpecific, 0, sizeof(codecSpecific));
-  }
+  CodecSpecificInfo() : codecType(kVideoCodecUnknown), codec_name(nullptr) {}
   VideoCodecType codecType;
   const char* codec_name;
   CodecSpecificInfoUnion codecSpecific;