busybox/menuconfig:
 * fix menuconfig prompts and help texts (no unnecessary FREETZ_BUSYBOX_ anymore)
 * refs #1786, in particular http://freetz.org/ticket/1786#comment:108
 * optimize performance of source:trunk/make/busybox/generate.sh


git-svn-id: file:///var/svn/freetz/trunk@9952 149334a1-2f27-0410-a3b9-fc62619ac1e6