Gate the internal H264 fallback in Create() on the probe result

GetSupportedFormats() no longer advertises the internal H264 formats
when the probe fails, but Create() still handed back the broken FFmpeg
decoder when the platform factories reject a format (e.g. a
profile-level-id VideoToolbox does not match). Gate the fallback on the
same probe so that path returns nullptr with a clear "No VideoDecoder
found" error instead of a decoder that fails Configure() at runtime.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: MaxHeimbrock

webrtc-sys/src/video_decoder_factory.cpp

@@ -157,7 +157,8 @@ std::unique_ptr<webrtc::VideoDecoder> VideoDecoderFactory::Create(
     return webrtc::CreateVp8Decoder(env);
   if (absl::EqualsIgnoreCase(format.name, webrtc::kVp9CodecName))
     return webrtc::VP9Decoder::Create();
-  if (absl::EqualsIgnoreCase(format.name, webrtc::kH264CodecName))
+  if (absl::EqualsIgnoreCase(format.name, webrtc::kH264CodecName) &&
+      internal_h264_decoder_works_)
     return webrtc::H264Decoder::Create();