Modifies SDK and iOS detection for helper method that needs iOS 9+

webrtc/modules/audio_device/ios/audio_device_ios.mm

Index: webrtc/modules/audio_device/ios/audio_device_ios.mm
diff --git a/webrtc/modules/audio_device/ios/audio_device_ios.mm b/webrtc/modules/audio_device/ios/audio_device_ios.mm
index 2551dad76d856241fb3a058a5aa83b429276ff33..4390f4925832986d0cfa7a56349711e9febc8374 100644
--- a/webrtc/modules/audio_device/ios/audio_device_ios.mm
+++ b/webrtc/modules/audio_device/ios/audio_device_ios.mm
@@ -262,14 +262,17 @@ static void LogDeviceInfo() {
   LOG(LS_INFO) << "LogDeviceInfo";
   @autoreleasepool {
     LOG(LS_INFO) << " system name: " << ios::GetSystemName();
-    LOG(LS_INFO) << " system version: " << ios::GetSystemVersion();
+    LOG(LS_INFO) << " system version 1(2): " << ios::GetSystemVersionAsString();

[tkchin_webrtc, 2016/03/02 19:23:45]

do we need both?

[henrika_webrtc, 2016/03/03 13:55:25]

If you don't mind I think we should keep both. Today we have:

[2823] (audio_device_ios.mm:265):  system version 1(2): 9.2.1
[2823] (audio_device_ios.mm:266):  system version 2(2): 9.2

hence, the x.x.1 is missing for the double representation. Ping me if you
disagree. I will land as is.

+    LOG(LS_INFO) << " system version 2(2): " << ios::GetSystemVersion();
     LOG(LS_INFO) << " device type: " << ios::GetDeviceType();
     LOG(LS_INFO) << " device name: " << ios::GetDeviceName();
     LOG(LS_INFO) << " process name: " << ios::GetProcessName();
     LOG(LS_INFO) << " process ID: " << ios::GetProcessID();
     LOG(LS_INFO) << " OS version: " << ios::GetOSVersionString();
     LOG(LS_INFO) << " processing cores: " << ios::GetProcessorCount();
+#if defined(__IPHONE_9_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_9_0
     LOG(LS_INFO) << " low power mode: " << ios::GetLowPowerModeEnabled();
+#endif
   }
 }
 #endif  // !defined(NDEBUG)