Don't redefine 'closefrom' if available through glibc.

Shamelessly stolen from Gentoo:

  https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-fs/fuse/files/fuse-2.9.9-closefrom-glibc-2-34.patch

diff --git a/configure.ac b/configure.ac
index 9946a0efa..a2d481aa9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,6 +55,7 @@ fi
 
 AC_CHECK_FUNCS([fork setxattr fdatasync splice vmsplice utimensat])
 AC_CHECK_FUNCS([posix_fallocate])
+AC_CHECK_FUNCS([closefrom])
 AC_CHECK_MEMBERS([struct stat.st_atim])
 AC_CHECK_MEMBERS([struct stat.st_atimespec])
 
diff --git a/util/ulockmgr_server.c b/util/ulockmgr_server.c
index 273c7d923..a04dac5c6 100644
--- a/util/ulockmgr_server.c
+++ b/util/ulockmgr_server.c
@@ -22,6 +22,10 @@
 #include <sys/socket.h>
 #include <sys/wait.h>
 
+#ifdef HAVE_CONFIG_H
+	#include "config.h"
+#endif
+
 struct message {
 	unsigned intr : 1;
 	unsigned nofd : 1;
@@ -124,6 +128,7 @@ static int receive_message(int sock, void *buf, size_t buflen, int *fdp,
 	return res;
 }
 
+#if !defined(HAVE_CLOSEFROM)
 static int closefrom(int minfd)
 {
 	DIR *dir = opendir("/proc/self/fd");
@@ -141,6 +146,7 @@ static int closefrom(int minfd)
 	}
 	return 0;
 }
+#endif
 
 static void send_reply(int cfd, struct message *msg)
 {
a class='active' href='/guix/log/gnu/packages/patches/nautilus-extension-search-path.patch'>log</a><a href='/guix/tree/gnu/packages/patches/nautilus-extension-search-path.patch?id=6b792019561d378c92d903d0dc53c3e9719f0fbd'>tree</a><a href='/guix/commit/gnu/packages/patches/nautilus-extension-search-path.patch?id=6b792019561d378c92d903d0dc53c3e9719f0fbd'>commit</a><a href='/guix/diff/gnu/packages/patches/nautilus-extension-search-path.patch?id=6b792019561d378c92d903d0dc53c3e9719f0fbd'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/patches/nautilus-extension-search-path.patch'>
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<tr><td><span title='2022-11-20 23:20:32 +0100'>2022-11-20</span></td><td><a href='/guix/commit/gnu/packages/patches/nautilus-extension-search-path.patch?id=99ba4ddb03b396f56764a25317f40d4501380704'>gnu: nautilus: Fix crash due to loading extensions twice.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/58221&gt;.
Reported by Tobias Kortkamp &lt;tobias.kortkamp@gmail.com&gt;.

Previously, if NAUTILUS_EXTENSION_PATH contained the same directory
several times, Nautilus could end up loading the same extension a second
time and crash.  This patch ensures that each extension cannot be loaded
more than once.

* gnu/packages/patches/nautilus-extension-search-path.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/gnome.scm (nautilus)[source]: Use it.
[arguments]: Remove 'make-extensible' phase.
</span></span></td><td>Ludovic Courtès</td></tr>