Fix build failure on glibc 2.28 where 'renameat2' would end up being
declared twice: <https://github.com/systemd/casync/issues/166>.

From 625244ca47e8ee1375d2d0092271bfd13b0913ea Mon Sep 17 00:00:00 2001
From: Daniel Mack <daniel@zonque.org>
Date: Tue, 13 Nov 2018 17:52:48 +0100
Subject: [PATCH] meson.build: pass -D_GNU_SOURCE when checking for functions

As described in #166, -D_GNU_SOURCE needs to be passed to the meson function
availability checker. h/t to @tomeon for providing a link to the solution as
well.
---
 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index f42ed16..c0f741e 100644
--- a/meson.build
+++ b/meson.build
@@ -78,6 +78,6 @@ foreach ident : [
         ['copy_file_range',   '''#include <sys/syscall.h>
                                  #include <unistd.h>'''],
 ]
-        have = cc.has_function(ident[0], prefix : ident[1])
+        have = cc.has_function(ident[0], args : '-D_GNU_SOURCE', prefix : ident[1])
         conf.set10('HAVE_' + ident[0].to_upper(), have)
 endforeach
x/refs/?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>refs</a><a class='active' href='/guix/log/tests/rpm.scm'>log</a><a href='/guix/tree/tests/rpm.scm?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>tree</a><a href='/guix/commit/tests/rpm.scm?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>commit</a><a href='/guix/diff/tests/rpm.scm?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/rpm.scm'>
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<div class='path'>path: <a href='/guix/log/?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>root</a>/<a href='/guix/log/tests?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>tests</a>/<a href='/guix/log/tests/rpm.scm?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3'>rpm.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/rpm.scm?id=7cf39c3ed410ec1e1b14c2c0bc6da692aaf212e3&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-02-19 21:13:23 -0500'>2023-02-19</span></td><td><a href='/guix/commit/tests/rpm.scm?id=598f4c509bbfec2b983a8ee246cce0a0fe45ec7f'>pack: Add RPM format.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/rpm.scm: New file.
* guix/scripts/pack.scm (rpm-archive): New procedure.
(%formats): Register it.
(show-formats): Add it.
(guix-pack): Register supported extra-options for the rpm format.
* tests/pack.scm (rpm-for-tests): New variable.
("rpm archive can be installed/uninstalled"): New test.
* tests/rpm.scm: New test.
* doc/guix.texi (Invoking guix pack): Document it.
</span></span></td><td>Maxim Cournoyer</td></tr>