configure wants C++ although not needed
liboggs (1.1.3 tarball from website) configure wants a working C++ compiler installed, but libogg has no parts written in C++. Therefore it's a useless dependency which should be removed.
By patching configure script not to exit if it can't find a C++ compiler (it actually fails the "sanity check", which none can ever pass), I was able to make it build and running. As my autoconf installation is broken I had no chance to cleanly fix this in the source files.