@abbaspour:
Yup, -static-libstdc++
But, again, that should be the default (
https://github.com/koreader/koreader...file.defs#L193 &&
https://github.com/koreader/koreader...efile.defs#L86).
And it's explicitly always done for cre, AFAICT (
https://github.com/koreader/koreader.../Makefile#L288 &&
https://github.com/koreader/koreader.../Makefile#L187).
So, err, again, make sure nothing in your env is polluting *FLAGS or that you're not overriding them by passing them to make on the CLI.
As you can see, the Makefiles are a house of cards tailored to the buildbot and the envs of a few developers, I've always directly messed w/ Makefiles.defs when I needed to adapt stuff to my TC, that's the safest move.
(Also, you shouldn't have had to mess with cmake's rules for cre).