util-linux: build schedutils without enabling basic binaries

Pull an upstream fix to allow building schedutils (ionice, taskset,
chrt) when util-linux is configured with

  $ configure --disable-all-programs --enable-schedutils

Fixes:
  https://bugs.busybox.net/show_bug.cgi?id=9656

Reported-by: Aaron Holtzman <aholtzma@gmail.com>
Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/util-linux/0003-build-sys-fix-disable-all-programs-enable-schedutils.patch

@@ -0,0 +1,99 @@
+From 6f2eb03433bcb2d3c351efed848a1f8554a7ff78 Mon Sep 17 00:00:00 2001
+From: Karel Zak <kzak@redhat.com>
+Date: Mon, 20 Feb 2017 14:17:37 +0100
+Subject: [PATCH] build-sys: fix --disable-all-programs --enable-schedutils
+
+* add UL_ENABLE_ALIAS(NAME, MASTERNAME) to initialize $enable_<name>
+  according to MASTERNAME. Note that we have to use $build_<mastername>,
+  the $enable_<mastername> is just AC_ARG_ENABLE() stuff only. The
+  $build_ is evaluated and modified by our UL_...() functions.
+
+* add enable-schedutils.conf to have build-system regression test for
+  this use-case
+
+Addresses: https://github.com/karelzak/util-linux/issues/415
+Signed-off-by: Karel Zak <kzak@redhat.com>
+---
+ configure.ac                              | 14 ++++++++------
+ m4/ul.m4                                  | 15 +++++++++++++++
+ tools/config-gen.d/enable-schedutils.conf |  3 +++
+ 3 files changed, 26 insertions(+), 6 deletions(-)
+ create mode 100644 tools/config-gen.d/enable-schedutils.conf
+
+diff --git a/configure.ac b/configure.ac
+index ad241fe..be282f0 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -1909,8 +1909,9 @@ AC_ARG_ENABLE([schedutils],
+ )
+ UL_BUILD_INIT([schedutils])
+ 
+-UL_BUILD_INIT([ionice], [check])
+-UL_REQUIRES_BUILD([ionice], [schedutils])
++
++UL_ENABLE_ALIAS([ionice], [schedutils])
++UL_BUILD_INIT([ionice])
+ UL_REQUIRES_SYSCALL_CHECK([ionice],
+ 	[UL_CHECK_SYSCALL([ioprio_set],
+ 	  [alpha],	[442],
+@@ -1937,8 +1938,9 @@ UL_REQUIRES_SYSCALL_CHECK([ionice],
+ 
+ AM_CONDITIONAL([BUILD_IONICE], [test "x$build_ionice" = xyes])
+ 
+-UL_BUILD_INIT([taskset], [check])
+-UL_REQUIRES_BUILD([taskset], [schedutils])
++
++UL_ENABLE_ALIAS([taskset], [schedutils])
++UL_BUILD_INIT([taskset])
+ UL_REQUIRES_HAVE([taskset], [cpu_set_t], [cpu_set_t type])
+ UL_REQUIRES_SYSCALL_CHECK([taskset],
+ 	[UL_CHECK_SYSCALL([sched_getaffinity])],
+@@ -1950,8 +1952,8 @@ have_schedsetter=no
+ AS_IF([test "x$ac_cv_func_sched_setscheduler" = xyes], [have_schedsetter=yes],
+       [test "x$ac_cv_func_sched_setattr" = xyes], [have_schedsetter=yes])
+ 
+-UL_BUILD_INIT([chrt], [check])
+-UL_REQUIRES_BUILD([chrt], [schedutils])
++UL_ENABLE_ALIAS([chrt], [schedutils])
++UL_BUILD_INIT([chrt])
+ UL_REQUIRES_HAVE([chrt], [schedsetter], [sched_set functions])
+ AM_CONDITIONAL([BUILD_CHRT], [test "x$build_chrt" = xyes])
+ 
+diff --git a/m4/ul.m4 b/m4/ul.m4
+index f8a0dd7..ed7227c 100644
+--- a/m4/ul.m4
++++ b/m4/ul.m4
+@@ -429,6 +429,21 @@ AC_DEFUN([UL_DEFAULT_ENABLE], [
+   fi
+ ])
+ 
++
++dnl UL_ENABLE_ALIAS(NAME, MASTERNAME)
++dnl
++dnl Initializes $enable_<name> variable according to $build_<mastername>.  This
++dnl is usefull for example if you want to use one --enable-mastername option
++dnl for group of programs.
++dnl
++AC_DEFUN([UL_ENABLE_ALIAS], [
++  m4_define([suffix], $1)
++  m4_define([mastersuffix], $2)
++
++  enable_[]suffix=$build_[]mastersuffix
++])
++
++
+ dnl UL_NCURSES_CHECK(NAME)
+ dnl
+ dnl Initializes $have_<name>, NCURSES_LIBS and NCURSES_CFLAGS variables according to
+diff --git a/tools/config-gen.d/enable-schedutils.conf b/tools/config-gen.d/enable-schedutils.conf
+new file mode 100644
+index 0000000..08deee4
+--- /dev/null
++++ b/tools/config-gen.d/enable-schedutils.conf
+@@ -0,0 +1,3 @@
++include:disable-all.conf
++
++--enable-schedutils
+-- 
+2.7.4
+

package/util-linux/util-linux.mk

@@ -8,8 +8,8 @@ UTIL_LINUX_VERSION_MAJOR = 2.29
 UTIL_LINUX_VERSION = $(UTIL_LINUX_VERSION_MAJOR).1
 UTIL_LINUX_SOURCE = util-linux-$(UTIL_LINUX_VERSION).tar.xz
 UTIL_LINUX_SITE = $(BR2_KERNEL_MIRROR)/linux/utils/util-linux/v$(UTIL_LINUX_VERSION_MAJOR)
-# For 0001-build-sys-use-lm-for-scriptreplay-if-necessary.patch and
-# 0002-build-sys-improve-detection-of-the-isnan-function-in.patch
+
+# Required because of the patches for configure.ac.
 UTIL_LINUX_AUTORECONF = YES
 
 # README.licensing claims that some files are GPLv2-only, but this is not true.