Fix NSInteger formatting warning from clang 6

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCCameraVideoCapturer.m

 /*
  *  Copyright 2017 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.
  */
 
@@ skipping 103 matching lines @@
   return eligibleDeviceFormats;
 }
 
 - (void)startCaptureWithDevice:(AVCaptureDevice *)device
                         format:(AVCaptureDeviceFormat *)format
                            fps:(NSInteger)fps {
   _willBeRunning = true;
   [RTCDispatcher
       dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                     block:^{
-                      RTCLogInfo("startCaptureWithDevice %@ @ %zd fps", format, fps);
+                      RTCLogInfo("startCaptureWithDevice %@ @ %ld fps", format, (long)fps);
 
 #if TARGET_OS_IPHONE
                       [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
 #endif
 
                       _currentDevice = device;
 
                       NSError *error = nil;
                       if (![_currentDevice lockForConfiguration:&error]) {
                         RTCLogError(
@@ skipping 281 matching lines @@
     case UIDeviceOrientationFaceUp:
     case UIDeviceOrientationFaceDown:
     case UIDeviceOrientationUnknown:
       // Ignore.
       break;
   }
 #endif
 }
 
 @end