clang-tidy: address google-readability-casting lint

ProcessUNIX.c

@@ -1370,11 +1370,13 @@ int kwsysProcess_WaitForExit(kwsysProcess* cp, double* userTimeout)
         cp->ProcessResults[prPipe].State = kwsysProcess_StateByIndex_Exited;
         cp->ProcessResults[prPipe].ExitException = kwsysProcess_Exception_None;
         cp->ProcessResults[prPipe].ExitValue =
+          // NOLINTNEXTLINE(google-readability-casting)
           (int)WEXITSTATUS(cp->ProcessResults[prPipe].ExitCode);
       } else if (WIFSIGNALED(cp->ProcessResults[prPipe].ExitCode)) {
         /* The child received an unhandled signal.  */
         cp->ProcessResults[prPipe].State = kwsysProcess_State_Exception;
         kwsysProcessSetExitExceptionByIndex(
+          // NOLINTNEXTLINE(google-readability-casting)
           cp, (int)WTERMSIG(cp->ProcessResults[prPipe].ExitCode), prPipe);
       } else {
         /* Error getting the child return code.  */