Added api/webrtcsdp.h forwarding header to work around upstream projects.

webrtc/api/webrtcsdp.h

Index: webrtc/api/webrtcsdp.h
diff --git a/webrtc/api/webrtcsdp.h b/webrtc/api/webrtcsdp.h
new file mode 100644
index 0000000000000000000000000000000000000000..bd7809a2c7e69b34745adab48aa3d867c5662c7d
--- /dev/null
+++ b/webrtc/api/webrtcsdp.h
@@ -0,0 +1,18 @@
+/*
+ *  Copyright 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_API_WEBRTCSDP_H_
+#define WEBRTC_API_WEBRTCSDP_H_
+
+// Including this file is deprecated. It is no longer part of the public API.
+// This only includes the file in its new location for backwards compatibility.
+#include "webrtc/pc/webrtcsdp.h"
+
+#endif  // WEBRTC_API_WEBRTCSDP_H_