Add a 'type lookup' command. This command is meant to look up type information by name in a language-specific way.

Currently, it only supports Objective-C - C++ types can be looked up through debug info via 'image lookup -t', whereas ObjC types via this command are looked up by runtime introspection

This behavior is in line with type lookup's behavior in Xcode 7, but I am definitely open to feedback as to what makes the most sense here

llvm-svn: 249047
diff --git a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
index 0e3c45f..09ee55d 100644
--- a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
+++ b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
@@ -146,6 +146,9 @@
     std::vector<ConstString>
     GetPossibleFormattersMatches (ValueObject& valobj, lldb::DynamicValueType use_dynamic) override;
     
+    std::unique_ptr<TypeScavenger>
+    GetTypeScavenger () override;
+    
     //------------------------------------------------------------------
     // Static Functions
     //------------------------------------------------------------------