It seems, that openwrt fails to build on clean minimal install of ubuntu server 16.04 lts, because it is missing python-dev package, so I needed to run sudo apt install python-dev yet after what is stated in wiki. So I went to edit wiki page and there's This wiki is read only and for archival purposes only. >>>>>>>>>> Please use the new OpenWrt wiki at https://openwrt.org/ <<<<<<<<<<
And that is where?
Also all search engines, posts, etc direct to the old wiki. Whereever the new wiki is, I don't think that burning bridges is a good idea. There should be at least valid clickable link to the new wiki.
And this is probably the problem.
I tried exactly the same link yet haven't found what I was looking for - what to install to satisfy dependencies before compiling. Shame, that old wiki is read only, I use it a lot, even edited missing info sometimes (as I wanted today). It's so full of informations, easy to use, search engines find whatever I look for in the first link. I don't get why to destroy something that worked so perfectly?