stdlib.h compilation error for macports gcc9.

[Ryan Schmidt]

On Feb 7, 2021, at 17:57, Ken Cunningham wrote:

> Perhaps we should find a way to broaden that down to including MacOSX10.15+ as well, if Catalina is going to be using the MacOSX11.x SDK.

Why stop at 10.15? For several macOS versions before that, the last compatible Xcode version might include only a newer SDK that does not match the OS version.