[Swan-commit] Changes to ref refs/heads/main

[Andrew Cagney]

New commits:
commit 0d3a1ed08d99bee774d7c5c25492fa7ab0358ba8
Author: Andrew Cagney <cagney at gnu.org>
Date:   Wed Oct 21 10:52:10 2020 -0400

    building: on GNU/Linux, define _GNU_SOURCE
    
    This is so that declarations for functions such as pipe2(,O_*) are
    exposed.  See #373.