patch 8.2.4744: a terminal window can't use the bell

Problem:    A terminal window can't use the bell.
Solution:   Add bell support for the terminal window. (closes #10178)

src/gui_w32.c

@@ -1696,7 +1696,7 @@ gui_mch_haskey(char_u *name)
     void
 gui_mch_beep(void)
 {
-    MessageBeep(MB_OK);
+    MessageBeep((UINT)-1);
 }
 /*
  * Invert a rectangle from row r, column c, for nr rows and nc columns.

src/option.h

@@ -451,7 +451,8 @@ EXTERN unsigned	bo_flags;
 #define BO_REG		0x8000
 #define BO_SH		0x10000
 #define BO_SPELL	0x20000
-#define BO_WILD		0x40000
+#define BO_TERM		0x40000
+#define BO_WILD		0x80000
 
 #ifdef FEAT_WILDIGN
 EXTERN char_u	*p_bsk;		// 'backupskip'

src/optionstr.c

@@ -20,7 +20,7 @@ static char *(p_bo_values[]) = {"all", "backspace", "cursor", "complete",
 				 "copy", "ctrlg", "error", "esc", "ex",
 				 "hangul", "insertmode", "lang", "mess",
 				 "showmatch", "operator", "register", "shell",
-				 "spell", "wildmode", NULL};
+				 "spell", "term", "wildmode", NULL};
 static char *(p_nf_values[]) = {"bin", "octal", "hex", "alpha", "unsigned", NULL};
 static char *(p_ff_values[]) = {FF_UNIX, FF_DOS, FF_MAC, NULL};
 #ifdef FEAT_CRYPT

src/terminal.c

@@ -3385,12 +3385,22 @@ handle_postponed_scrollback(term_T *term)
     limit_scrollback(term, &term->tl_scrollback, TRUE);
 }
 
+/*
+ * Called when the terminal wants to ring the system bell.
+ */
+    static int
+handle_bell(void *user UNUSED)
+{
+    vim_beep(BO_SH);
+    return 0;
+}
+
 static VTermScreenCallbacks screen_callbacks = {
   handle_damage,	// damage
   handle_moverect,	// moverect
   handle_movecursor,	// movecursor
   handle_settermprop,	// settermprop
-  NULL,			// bell
+  handle_bell,		// bell
   handle_resize,	// resize
   handle_pushline,	// sb_pushline
   NULL			// sb_popline

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4744,
 /**/
     4743,
 /**/