Avoid conflicts between different GCC installations
Avoid conflicts between different GCC installations

* Depends on external formulae ecj, drop internal ecj logic.
* Remove #{prefix}/share/man/man7.
* Backport changes from up-to-date GCC version
  - New option syntax.
  - Multilib support.
  - Xcode-only support.

Closes #64.

Signed-off-by: Jack Nagel <43386ce32af96f5c56f2a88e458cb94cebee3751@gmail.com>

heuermh/homebrew-versions,coeligena/homebrew-verscustomized,DomT4/homebrew-versions,jimhe/homebrew-versions,UniqMartin/homebrew-versions,Ashton-W/homebrew-versions