Introduce and use FileName::exists()

This can use the faster route through QFileInfo::exist now.

Change-Id: Idb41b5d5185d7f02eacba498fb01f483d95e8d57
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
Reviewed-by: Christian Stenger <christian.stenger@digia.com>

src/plugins/ios/iostoolhandler.cpp

@@ -738,7 +738,7 @@ QString IosToolHandler::iosSimulatorToolPath()
     Utils::FileName devPath = Internal::IosConfigurations::developerPath();
     bool version182 = devPath.appendPath(QLatin1String(
         "Platforms/iPhoneSimulator.platform/Developer/Library/PrivateFrameworks/iPhoneSimulatorRemoteClient.framework"))
-            .toFileInfo().exists();
+            .exists();
     QString res = Core::ICore::libexecPath() + QLatin1String("/ios/iossim");
     if (version182)
         res = res.append(QLatin1String("_1_8_2"));