macosx_deployment_target - building for previous versions from MacOS 10.13

[Friedrich Beckmann]

> Am 05.09.2020 um 08:39 schrieb Ryan Schmidt <ryandesign at macports.org>:
> 
> On Sep 4, 2020, at 05:53, Friedrich Beckmann wrote:
> 
>> :info:configure checking if /usr/bin/clang++ works... no
>> :info:configure configure: WARNING: Ignore /usr/bin/clang++, since it cannot compile hello-world.
>> :info:configure configure: WARNING: You don't have any C++ compiler, too bad
>> 
>> because the 10.5 and libc++ does not fit as you say.
> 
> You'd need to examine the config.log to see why it failed.

It is because clang++ says it cannot compile with deployment target „10.5" and "-stdlib=libc++“. So for the ncurses port it would be possible to change to „-stdlib=libstdc++“ if the deployment target is below 10.7