Go back to the interpreter main loop after performing intrinsic lowering,

because 1) the first instruction might not be a call site, and
2) CS and SF.Caller were not getting set to point to the new call site
anyway (resulting in a crash on e.g. call %llvm.memset).

llvm-svn: 13122

llvm/lib/ExecutionEngine/Interpreter/Execution.cpp

@@ -822,6 +822,7 @@ void Interpreter::visitCallSite(CallSite CS) {
         SF.CurInst = Prev;
         ++SF.CurInst;
       }
+      return;
     }
 
   SF.Caller = CS;