input: make <Shift+Tab> do an unindent also on a Manjaro console

This fixes https://savannah.gnu.org/bugs/?52943.

src/winio.c

@@ -388,6 +388,8 @@ int parse_kbinput(WINDOW *win)
 		case 1:
 			if (keycode >= 0x80)
 				retval = keycode;
+			else if (keycode == TAB_CODE)
+				retval = SHIFT_TAB;
 			else if ((keycode != 'O' && keycode != 'o' && keycode != '[') ||
 						key_buffer_len == 0 || *key_buffer == ESC_CODE) {
 				/* One escape followed by a single non-escape: