Yes, I am aware that this is an old topic, but I got stuck with the same issue just now I managed to get past - maybe it will help someone. Who knows...

Please use the steps described by Flemming Richter above just change the Makefile URL to https://raw.githubusercontent.com/openwrt/packages/master/libs/libugpio/Makefile

It worked for me flawlessly.

Yes, I am aware that this is an old topic, but I got stuck with the same issue just now I managed to get past - maybe it will help someone. Who knows...

Please use the steps described by Flemming Richter above just change the Makefile URL to https://raw.githubusercontent.com/openwrt/packages/master/libs/libugpio/Makefile

It worked for me flawlessly.