Multithreading Library

[Sjoerd van Leent]

On some machines it is necessary to link in the gcc_s library, otherwise,
the Unwind_* functions are not found. I wonder whether it is possible to
let gdc automatically link it in, since it is necessary even for the most
simplistic binaries.

If this isn't possible, perhaps it would be practical to at least be able to
build gdc in such a way with some kind of configuration parameter.

Sjoerd