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

diff -purN bash-5.0-orig/configure bash-5.0/configure
--- configure	1970-01-01 01:00:00.000000000 +0100
+++ configure	2019-09-29 11:51:42.664518665 +0200
@@ -16312,11 +16312,7 @@ solaris2.10*)	LOCAL_CFLAGS=-DSOLARIS  ;;
 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" ;;
diff -purN bash-5.0-orig/configure.ac bash-5.0/configure.ac
--- configure.ac	1970-01-01 01:00:00.000000000 +0100
+++ configure.ac	2019-09-29 11:51:10.692026225 +0200
@@ -1108,10 +1108,7 @@ solaris2.10*)	LOCAL_CFLAGS=-DSOLARIS  ;;
 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" ;;
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<div class='path'>path: <a href='/guix/log/?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182'>root</a>/<a href='/guix/log/gnu?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182'>gnu</a>/<a href='/guix/log/gnu/installer?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182'>installer</a>/<a href='/guix/log/gnu/installer/newt?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182'>newt</a>/<a href='/guix/log/gnu/installer/newt/timezone.scm?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182'>timezone.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/installer/newt/timezone.scm?id=06f4dc2bf62a0fea7577bf917aa3a4cb6ca6b182&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-02-02 16:46:44 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/installer/newt/timezone.scm?id=726d0bd2f36363392ba2fcefd6e5d4aeed27dc9e'>installer: Use named prompt to abort or break installer steps.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/steps.scm (run-installer-steps): Set up
'installer-step prompt.
* gnu/installer/newt/ethernet.scm (run-ethernet-page)
* gnu/installer/newt/final.scm (run-config-display-page,
run-install-failed-page)
* gnu/installer/newt/keymap.scm (run-layout-page, run-variant-page)
* gnu/installer/newt/locale.scm (run-language-page,
run-territory-page, run-codeset-page, run-modifier-page,
run-locale-page)
* gnu/installer/newt/network.scm (run-technology-page,
wait-service-online)
* gnu/installer/newt/page.scm (run-listbox-selection-page,
run-checkbox-tree-page)
* gnu/installer/newt/partition.scm (button-exit-action)
* gnu/installer/newt/services.scm (run-desktop-environments-cbt-page,
run-networking-cbt-page, run-other-services-cbt-page,
run-network-management-page)
* gnu/installer/newt/timezone.scm (run-timezone-page)
* gnu/installer/newt/user.scm (run-user-page)
* gnu/installer/newt/welcome.scm (run-menu-page)
* gnu/installer/newt/wifi.scm (run-wifi-page): Use the 'installer-step
prompt to abort.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>