add missing dependency to mksh

Config.in

@@ -44,6 +44,7 @@ config ADK_DEVELSYSTEM
 	select ADK_PACKAGE_LIBTOOL
 	select ADK_PACKAGE_M4
 	select ADK_PACKAGE_MAKE
+	select ADK_PACKAGE_MKSH
 	select ADK_PACKAGE_PATCH
 	select ADK_PACKAGE_MICROPERL
 	select ADK_PACKAGE_TAR