Merge pull request #10563 from adrian-prantl/cherry-pick-next-lldb-Factor-out-iteration-over-runtime-types-from-GetChildCompilerTypeAtIndex

[Cherry-pick into next] [lldb] Factor out iteration over runtime types from GetChildCompilerTypeAtIndex()

Author: adrian-prantl

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.h

@@ -67,6 +67,8 @@ struct SuperClassType;
 using ThreadSafeReflectionContext = LockGuarded<ReflectionContextInterface>;
 
 class SwiftLanguageRuntime : public LanguageRuntime {
+  friend class SwiftRuntimeTypeVisitor;
+
 protected:
   SwiftLanguageRuntime(Process &process);