Fix a check in the objc trampoline handler

[sas]

Summary

The function FunctionCaller::WriteFunctionArguments returns false on
errors, so they should check for the false return value.

Change by Walter Erquinigo <[e-mail]>

source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp

AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread, ValueList &dispatch_values)
     }
 
     diagnostics.Clear();
 
     // Now write down the argument values for this particular call.  This looks like it might be a race condition
     // if other threads were calling into here, but actually it isn't because we allocate a new args structure for
     // this call by passing args_addr = LLDB_INVALID_ADDRESS...
 
-    if (impl_function_caller->WriteFunctionArguments(exe_ctx, args_addr, dispatch_values, diagnostics))
+    if (!impl_function_caller->WriteFunctionArguments(exe_ctx, args_addr, dispatch_values, diagnostics))
     {
         if (log)
         {
             log->Printf("Error writing function arguments.");
             diagnostics.Dump(log);
         }
         return args_addr;
     }