Unconditionally enable PGRP_PIPE on Linux (the kernel), regardless of
the kernel version in use on the build machine.

--- configure.ac.orig	2019-01-02 09:38:44.000000000 -0500
+++ configure.ac	2019-08-15 16:40:24.271758379 -0400
@@ -1108,10 +1108,7 @@
 solaris2*)	LOCAL_CFLAGS=-DSOLARIS ;;
 lynxos*)	LOCAL_CFLAGS=-DRECYCLES_PIDS ;;
 linux*)		LOCAL_LDFLAGS=-rdynamic		 # allow dynamic loading
-		case "`uname -r`" in
-		1.*|2.[[0123]]*)	: ;;
-		*)	AC_DEFINE(PGRP_PIPE) ;;
-		esac ;;
+		AC_DEFINE(PGRP_PIPE) ;;
 netbsd*|openbsd*)	LOCAL_CFLAGS="-DDEV_FD_STAT_BROKEN" ;;
 *qnx[[67]]*)	LOCAL_LIBS="-lncurses" ;;
 *qnx*)		LOCAL_CFLAGS="-Dqnx -F -3s" LOCAL_LDFLAGS="-3s" LOCAL_LIBS="-lunix -lncurses" ;;
--- configure.orig	2019-01-02 09:43:04.000000000 -0500
+++ configure	2019-08-15 16:41:44.440155912 -0400
@@ -16312,11 +16312,7 @@
 solaris2*)	LOCAL_CFLAGS=-DSOLARIS ;;
 lynxos*)	LOCAL_CFLAGS=-DRECYCLES_PIDS ;;
 linux*)		LOCAL_LDFLAGS=-rdynamic		 # allow dynamic loading
-		case "`uname -r`" in
-		1.*|2.[0123]*)	: ;;
-		*)	$as_echo "#define PGRP_PIPE 1" >>confdefs.h
- ;;
-		esac ;;
+		$as_echo "#define PGRP_PIPE 1" >>confdefs.h ;;
 netbsd*|openbsd*)	LOCAL_CFLAGS="-DDEV_FD_STAT_BROKEN" ;;
 *qnx[67]*)	LOCAL_LIBS="-lncurses" ;;
 *qnx*)		LOCAL_CFLAGS="-Dqnx -F -3s" LOCAL_LDFLAGS="-3s" LOCAL_LIBS="-lunix -lncurses" ;;
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<tr><td><span title='2023-02-09 01:07:47 +0100'>2023-02-09</span></td><td><a href='/guix/commit/gnu/tests/ganeti.scm?id=802ea1f3a43e5fb8d0b8bd2882954d8a6e49cde6'>system: Deprecate hosts-file.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system.scm (operating-system-hosts-file): Deprecate procedure.
(warn-hosts-file-field-deprecation): New procedure, helper for
deprecated variable.
(operating-system)[hosts-file]: Use helper to warn deprecated field.
(local-host-aliases): Mark as deprecated.
(local-host-entries): New procedure.
(operating-system-default-essential-services,
hurd-default-essential-services): Use hosts-service-type.  Use
'%operating-system-hosts-file' and 'local-host-entries'.
(default-/etc/hosts): Remove procedure.
(operating-system-etc-service): Remove hosts file.
* doc/guix.texi (operating-system Reference)
(Networking Services) (Virtualization Services): Rewrite documentation
entries to use hosts-service-type.

Co-authored-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Bruno Victal</td></tr>
<tr><td><span title='2021-12-13 11:49:15 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/tests/ganeti.scm?id=1052ae5f03de931b52c7a638c8e4f8d8d7093af3'>Merge branch 'master' into core-updates-frozen</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-12-12 23:20:50 +0100'>2021-12-12</span></td><td><a href='/guix/commit/gnu/tests/ganeti.scm?id=f73ba627abd46018da7f6f41ebd5efb99412cc54'>tests: Replace uses of deprecated 'static-networking-service'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/ganeti.scm (%ganeti-os): Replace call to
'static-networking-service' by instantiating
STATIC-NETWORKING-SERVICE-TYPE.
* gnu/tests/networking.scm (%test-static-networking)
(%openvswitch-os, %dhcpd-os): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>