Building GCC

I’ve improved and extended the GCC article into a general article on building (curse, spit, etc) GCC.

http://liblfds.org/mediawiki/index.php?title=Building_GCC

Matrix of GCC/dependency release dates, so you can try to figure out which versions to use, general advice, specific advice and currently explicit and tested instructions to build 4.4.3, which I will (God help me) be extending to cover all the versions of GCC which I can manage to make build.