Build dynamic iOS SDK.

- Places most ObjC code into webrtc/sdk/objc instead.
- New gyp targets to build, strip and export symbols for dylib.
- Removes old script used to generate dylib.

BUG=

Review URL: https://codereview.webrtc.org/1903663002

Cr-Commit-Position: refs/heads/master@{#12524}

webrtc/sdk/objc/Framework/Classes/RTCUIApplication.h

@@ -0,0 +1,21 @@
+/*
+ *  Copyright 2016 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_BASE_OBJC_RTC_UI_APPLICATION_H_
+#define WEBRTC_BASE_OBJC_RTC_UI_APPLICATION_H_
+
+#include "WebRTC/RTCMacros.h"
+
+#if defined(WEBRTC_IOS)
+/** Convenience function to get UIApplicationState from C++. */
+RTC_EXTERN bool RTCIsUIApplicationActive();
+#endif  // WEBRTC_IOS
+
+#endif  // WEBRTC_BASE_OBJC_RTC_UI_APPLICATION_H_