GCC47: 4.7.3.

* GCC 4.7 now can be bootstrapped by Clang. Drop fails_with part.
* Remove obsolete ENV.m64 part. GCC 4.7 detects host triplets.
* Apply patches from macports to fix debugging.
* Don't unset __GLIBCXX_DEBUG* as original bug didn't actually do that.
* Make arch and osmajor standalone functions, and construct host triplet
  for build.
* Integrate '--enable-languages' into args.

Closes #99.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
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.

Closes #100.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
Use opt_prefix to avoid broken link when dependencies upgrades.

* Don't unset __GLIBCXX_DEBUG* as original bug didn't actually do that.
* Make arch and osmajor standalone functions, and construct host triplet
  for build.
* Integrate '--enable-languages' into args.

Closes #102.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>