verbatim: insert the full code sequence when <Alt+Backspace> is pressed

(This could lead to unwanted behavior when the user wants to enter
a literal escape character (0x1B) while the input is somehow getting
stalled, because then a command keystroke after the M-V <Esc> would
get inserted verbatim too, instead of getting acted upon.  But that
is a small price to pay for getting the correct behavior for both
M-V M-Bsp and M-V M-Enter.)

This fixes https://savannah.gnu.org/bugs/?58909.

Bug existed since version 2.6.3, commit 08c51cfd,
but also occurred erratically beforehand.

src/winio.c

@@ -1420,9 +1420,9 @@ int *parse_verbatim_kbinput(WINDOW *win, size_t *count)
 
 	free(kbinput);
 
-	/* If this is an iTerm/Eterm/rxvt double escape, take both Escapes. */
-	if (key_buffer_len > 3 && *key_buffer == ESC_CODE &&
-				key_buffer[1] == ESC_CODE && key_buffer[2] == '[')
+	/* In case of an escape, take also a second code, as it might be another
+	 * escape (on iTerm2/rxvt) or a control code (for M-Bsp and M-Enter). */
+	if (key_buffer_len > 1 && *key_buffer == ESC_CODE)
 		*count = 2;
 
 	return get_input(NULL, *count);