Add return value for Make RdcStandaloneHandler::error_handle

Quiets compile warning.

Change-Id: I5e7454f56e824e2304c790bac729cfa0fcf78603

rdc_libs/rdc_client/src/RdcStandaloneHandler.cc

@@ -47,6 +47,7 @@ rdc_status_t RdcStandaloneHandler::error_handle(::grpc::Status status,
     if (rdc_status != RDC_ST_OK) {
         return static_cast<rdc_status_t>(rdc_status);
     }
+    return RDC_ST_OK;
 }
 
 // JOB RdcAPI