kconfig: highlight xconfig 'comment' lines with '***'

Mark Kconfig "comment" lines with "*** <commentstring> ***"
so that it is clear that these lines are comments and not some
kconfig item that cannot be modified.

This is helpful in some menus to be able to provide a menu
"sub-heading" for groups of similar config items.

This also makes the comments be presented in a way that is
similar to menuconfig and nconfig.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/qconf.cc

@@ -122,6 +122,7 @@ void ConfigItem::updateMenu(void)
 		goto set_prompt;
 	case P_COMMENT:
 		setIcon(promptColIdx, QIcon());
+		prompt = "*** " + prompt + " ***";
 		goto set_prompt;
 	default:
 		;