Tried to reproduce on CentOS 5.11.
Seems that nettle require newer GMP lib than comes with system.
I built GMP 6.1.2 in the setup that finally worked.
As I ended up building almost all the dependencies, except for basic
stuff like posix threads, it would not come as a big surprise to me if
the combination of newest MHD and GnuTLS would fail in the same way on
more modern platforms as well.
If anyone would like a copy of my build environment for further testing,
please let me know. I will settle for the working version I have got at
this point as far as RHEL5 is concerned.
Best regards,
Svein Olav Bjerkeset