This ticket adds system packages information for MacPorts,
a common macOS package manager.

The follow-up ticket #31505 extends the package scripts
to make use of them.

Related:

• Meta-ticket: spkg-configure: Try to use as many system packages as possible #27330: Meta-ticket: spkg-configure: Try to use as many system packages as possible
• Add more homebrew system package information, including packages without spkg-configure.m4 #30861: Add Homebrew package information

CC: @mkoeppe @slel

Component: build

Keywords: macports

Author: Samuel Lelièvre

Branch: b8b7092

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/30504