wxgtk-3.0: accept '-stdlib=' option

[mojca]

Description

For details see https://trac.macports.org/ticket/57092

I would prefer if someone else (like @kencu) would check and test this patch first. I also asked @vslavik to try to fix it upstream (I wasn't sure where upstream of this file was), once that is done, we need an upstream fix in wxWidgets as well.

We probably also need to fix wxgtk-3.2 and fix dependency on webkit-gtk (either always disable or always enable it) as a separate task.

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 10.x
Xcode 8.x

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL?

• checked your Portfile with port lint?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?

[kencu]

will test today

[kencu]

works perfectly on this system. Looks good!

[mojca]

Thank you.