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" ;;
ef='/guix/commit/gnu/services/pm.scm?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>commit</a><a href='/guix/diff/gnu/services/pm.scm?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/services/pm.scm'>
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<div class='path'>path: <a href='/guix/log/?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>root</a>/<a href='/guix/log/gnu?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>gnu</a>/<a href='/guix/log/gnu/services?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>services</a>/<a href='/guix/log/gnu/services/pm.scm?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd'>pm.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/gnu/services/pm.scm?id=0c89fe9e17dc9e628c73959289464ac5f146c7cd&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-03-20 16:40:22 +0100'>2022-03-20</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=10d865aa921f559562fb543d7796c7a08e17f016'>services: thermald: Add 'adaptive?' field.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/pm.scm (&lt;thermald-configuration&gt;): Add 'adaptive?' field.
(thermald-shepherd-service): Use it to pass --adaptive to thermald.
* doc/guix.texi (Power Management Services): Document the 'adaptive?' field of
'thermald-configuration'.
</span></span></td><td>Jelle Licht</td></tr>
<tr><td><span title='2022-02-02 10:43:04 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=67f28faf42a362ae4d50ede4cc48782e2aea887f'>services: tlp: Add config variables for battery charging.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/pm.scm (tlp-configuration): Add start-charge-thresh-bat0,
stop-charge-thresh-bat0, start-charge-thresh-bat1, stop-charge-thresh-bat1.
* doc/guix.texi (Power Management Services): Document them.

Signed-off-by: Ricardo Wurmus &lt;rekado@elephly.net&gt;
</span></span></td><td>Attila Lendvai</td></tr>
<tr><td><span title='2021-11-30 01:08:55 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=892f1b7273d57b25940700877a02618fe826cc08'>services: Accept &lt;inferior-package&gt;s in lieu of &lt;package&gt;s.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/authentication.scm (fprintd-configuration)
(nslcd-configuration): Substitute file-like objects for package ones.
* gnu/services/cgit.scm (cgit-configuration, opaque-cgit-configuration):
Likewise.
* gnu/services/cups.scm (package-list?, cups-configuration): Likewise.
* gnu/services/dns.scm (verify-knot-configuration)
(ddclient-configuration): Likewise.
* gnu/services/docker.scm (docker-configuration): Likewise.
* gnu/services/file-sharing.scm (transmission-daemon-configuration): Likewise.
* gnu/services/getmail.scm (getmail-configuration): Likewise.
* gnu/services/mail.scm (dovecot-configuration)
(opaque-dovecot-configuration): Likewise.
* gnu/services/messaging.scm (prosody-configuration)
(opaque-prosody-configuration): Likewise.
* gnu/services/monitoring.scm (zabbix-server-configuration)
(zabbix-agent-configuration): Likewise.
* gnu/services/networking.scm (opendht-configuration): Likewise.
* gnu/services/pm.scm (tlp-configuration): Likewise.
* gnu/services/telephony.scm (jami-configuration): Likewise.
* gnu/services/virtualization.scm (libvirt-configuration)
(qemu-guest-agent-configuration): Likewise.
* gnu/services/vpn.scm (openvpn-client-configuration): Likewise.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-02-02 10:42:16 +0100'>2020-02-02</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=8a890f3c40f698c976dc2a759ccc9c11641bd4f6'>gnu: tlp: Update to 1.3.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/linux.scm (tlp): Update to 1.3.0.
[source]: Hard-code name in origin URI.
[native-inputs]: Add "shellcheck".
[arguments]: Activate some tests.  Update environment variables.  Ignore
tlp-rdw man pages.
* gnu/services/pm.scm (tlp-activation): Update configuration file name.
</span></span></td><td>Nicolas Goaziou</td></tr>