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/Headers/WebRTC/RTCVideoRenderer.h

@@ -0,0 +1,33 @@
+/*
+ *  Copyright 2015 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.
+ */
+
+#import <Foundation/Foundation.h>
+#if TARGET_OS_IPHONE
+#import <UIKit/UIKit.h>
+#endif
+
+#import <WebRTC/RTCMacros.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class RTCVideoFrame;
+
+RTC_EXPORT
+@protocol RTCVideoRenderer <NSObject>
+
+/** The size of the frame. */
+- (void)setSize:(CGSize)size;
+
+/** The frame to be displayed. */
+- (void)renderFrame:(nullable RTCVideoFrame *)frame;
+
+@end
+
+NS_ASSUME_NONNULL_END