Anyway, building a compiler on the raspberry pi worked for me, although it took a long time to build. I created a new wiki page with build instructions: https://bitbucket.org/goshawk/gdc/wiki/Raspberry%20Pi
I've done some new attempts. After using a different OS image on a different SD card, everything worked much better (raspbian "Pisces"). I followed your instructions on the wiki page but had to change arm-linux-gnueabi to arm-linux-gnueabihf and later removed them altogether with the same effect.
However, compilation got stuck at the same place as before. It couldn't find <bits/predefs.h> and other architecture specific files. Symlinking from /usr/include/arm-linux-gnueabihf/* to gcc/* helped a bit until it stopped with the same error as in the build log that I posted before.
I will probably just try the debian image, although a system with hardfloat support would be pretty important in the long run. But the fact that it doesn't find the /sys/, /bits/ etc. headers sounds like it is just some stupid little build problem. But I'm much too unfamiliar with the GCC build process to make effective guesses for a solution.
