New formula: GCC 4.3.

* Track latest GCC 4.3 release.
* Adapt patches from macports.
* Use '--datadir' and '--mandir' as datarootdir was not supported yet.
* Don't unset __GLIBCXX_DEBUG* as original bug didn't actually do that.
* Use `uname -m` to detect architecture, `uname -r` to detect osmajor
  version.
* Make arch and osmajor standalone functions, and combine as host
  triplet for build.
* Integrate '--enable-languages' into args.
* Put utility functions inside the class body following @jacknagel's
  suggestion.