Yeah I'm having trouble with that too. Somebody here did manage to build it on Ubuntu, though; we should probably find out what exactly makes itwork / breaks it on Debian.
I don't know about Ubuntu, but on Debian Wheezy (rc1), GDC 4.8 builds without problems. For GDC 4.7 you need to either use patched GCC sources from Debian repositories or set
CPATH=/usr/include/x86_64-linux-gnu LIBRARY_PATH=/usr/lib/x86_64-linux-gnu
