Changed signature of GenerateMessageSend() function to pass the...

Changed signature of GenerateMessageSend() function to pass the ObjCInterfaceDecl for class messages and removed the boolean IsClassMessage argument, which wasn't used anywhere.

Emitted some metadata on message sends to allow a later pass to do some speculative inlining of class methods (GNU runtime).  Speculative inlining of instance methods requires type feedback to be useful (work in progress), but for class methods it works quite nicely.  

llvm-svn: 102514