patch 9.0.0571: MS-Windows: CTRL-C can make Vim exit

Problem:    MS-Windows: CTRL-C can make Vim exit.
Solution:   Check the not-a-term argument.
diff --git a/src/normal.c b/src/normal.c
index be578ae..0539738 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -6793,11 +6793,8 @@
 		&& !VIsual_active
 		&& no_reason)
 	{
-	    int	out_redir = !stdout_isatty
-#ifdef FEAT_GUI
-				&& !gui.in_use
-#endif
-				;
+	    int	out_redir = !stdout_isatty && !is_not_a_term_or_gui();
+
 	    // The user may accidentally do "vim file | grep word" and then
 	    // CTRL-C doesn't show anything.  With a changed buffer give the
 	    // message on stderr.  Without any changes might as well exit.