This is required for compiling Python 3.7

Tarball: ftp://sourceware.org/pub/libffi/libffi-3.2.1.tar.gz

CC: @embray

Component: packages: standard

Author: Jeroen Demeyer

Branch: e45cf27

Reviewer: Frédéric Chapoton, Erik Bray

Issue created by migration from https://trac.sagemath.org/ticket/25900