Remove compat for iOS 7/8

webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm

Index: webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm
diff --git a/webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm b/webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm
index e36c83bad9485517b69f9acea5ab5fde74ba3b0e..f12ff0002b5bb24df172c1ab102752b52b889ed0 100644
--- a/webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm
+++ b/webrtc/modules/video_capture/ios/rtc_video_capture_ios_objc.mm
@@ -44,11 +44,8 @@ using namespace webrtc::videocapturemodule;
     _owner = owner;
     _captureId = captureId;
     _captureSession = [[AVCaptureSession alloc] init];
-#if defined(__IPHONE_7_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_7_0
-    NSString* version = [[UIDevice currentDevice] systemVersion];
-    if ([version integerValue] >= 7) {
-      _captureSession.usesApplicationAudioSession = NO;
-    }
+#if defined(WEBRTC_IOS)
+    _captureSession.usesApplicationAudioSession = NO;
 #endif
     _captureChanging = NO;
     _captureChangingCondition = [[NSCondition alloc] init];