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.

src/main.c

@@ -1008,7 +1008,7 @@ common_init(mparm_T *paramp)
  * Return TRUE when the --not-a-term argument was found.
  */
     int
-is_not_a_term()
+is_not_a_term(void)
 {
     return params.not_a_term;
 }
@@ -1016,8 +1016,8 @@ is_not_a_term()
 /*
  * Return TRUE when the --not-a-term argument was found or the GUI is in use.
  */
-    static int
-is_not_a_term_or_gui()
+    int
+is_not_a_term_or_gui(void)
 {
     return params.not_a_term
 #ifdef FEAT_GUI

src/normal.c

@@ -6793,11 +6793,8 @@ nv_esc(cmdarg_T *cap)
 		&& !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.

src/proto/main.pro

@@ -2,6 +2,7 @@
 int vim_main2(void);
 void common_init(mparm_T *paramp);
 int is_not_a_term(void);
+int is_not_a_term_or_gui(void);
 char_u *get_gui_dialog_file(void);
 int op_pending(void);
 void may_trigger_safestate(int safe);

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    571,
 /**/
     570,
 /**/