Easier/better way to maintain package selection in source tree fork

[hnyman]

Just keep the short pruned version of diffconfig output as a .config recipe, as you only need the deviations from the standard, not all possible lines in the long .config

Programmatically (non-interactively) configure the OpenWrt build

The easiest thing is probably to manually craft a short .config recipe for each target, and then tailor it for each OpenWrt version. The .config recipe can easily be originally based on ./scripts/diffconfig.sh output I am building several community builds with that approach. (WNDR3700 with ar71xx and ath79 , R7800 ipq806x), and privately also WRT3200ACM mvebu, and I build master and 19.07 for all of them. Pretty easy, once you get the .config recipe for master. It usually needs only slight ch…