Ada & Fortran Support

@nordlow  In that case, we'll need to add (or change) an option cell, since Flycheck doesn't support this style of options currently.

For now, use `(eval (when flycheck-ada-gcc-language-standard) (s-concat "-" flycheck-ada-gcc-language-standard)))`.  I'll add a corresponding option cell and refactor the code after merging this PR.