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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>Author</th></tr>
<tr><td><span title='2020-04-06 00:14:13 +0200'>2020-04-06</span></td><td><a href='/guix/commit/gnu/system/keyboard.scm?id=2729cb406d9f3e9eb22cc660f887138134edb3a8'>system: Allow for comma-separated keyboard layouts.</a><span class='msg-avail'>...<span class='msg-tooltip'>Reported by Florian Pelz &lt;pelzflorian@pelzflorian.de&gt;.

* gnu/bootloader/grub.scm (keyboard-layout-file): Replace commas with
hyphens in the first argument to 'computed-file'.
* gnu/system/keyboard.scm (keyboard-layout-&gt;console-keymap): Likewise.
* doc/guix.texi (Keyboard Layout): Add example.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-03-24 23:06:11 +0100'>2019-03-24</span></td><td><a href='/guix/commit/gnu/system/keyboard.scm?id=db1e2522f6222594fc507ce7a7ba7b1c0ac5037d'>Add (gnu system keyboard).</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system/keyboard.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* gnu.scm (%public-modules): Add it.
</span></span></td><td>Ludovic Courtès</td></tr>