MacPorts 2.6 - Leopard 20.6 and libgcc8

[Riccardo Mottola]

Hi!

Chris Jones wrote:
> https://github.com/macports/macports-ports/commit/2e46a05404462e04930b612ed29d9f08ece64603
>
> I have no way though to test the logic on an OS as ancient as 10.5....

I patched the file locally in my macports.... then rerun build of 
harfbuzz and the dependency issue is gone.

harfbuzz tries to use gcc 6 and a lot of errors ! I forced clang 5.0 
.... and smooth harfbuzz upgraded!

I suppose this is an important fix for 10.5 user, we soon need a 2.6.1

Riccardo