Apple simulator platforms don't have a shared cache to load Objective-C class information from

This code was doing the right thing for the iOS simulator, but not other simulator platforms

Fix it by making the warning not happen for all platforms whose name ends in "-simulator"
Since this code lives in AppleObjCRuntimeV2.cpp, this already only applies to Apple platforms by definition, so I am not too worried about conflicts with other vendors

llvm-svn: 261165