udftools: fix static linking against readline

One program of udftools uses the readline library, but fails to build
in static linking configurations. In order to fix this, we teach
udftools configure.ac to use pkg-config to detect the readline
library, and to use the proper flags provided by pkg-config.

This obviously requires an autoreconf of the package, and the addition
of host-pkgconf in the dependencies.

Fixes:

  http://autobuild.buildroot.net/results/113a94049d89b8f065112e5d4482667a7b7fb843/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/udftools/0002-configure.ac-detect-readline-via-pkg-config-when-pos.patch

@@ -0,0 +1,60 @@
+From bdacf0101fea1dad2c89996b27cb4b9caee9109c Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+Date: Sun, 22 Apr 2018 22:28:09 +0200
+Subject: [PATCH] configure.ac: detect readline via pkg-config when possible
+
+pkg-config automatically handles static linking situations, where for
+example readline is linked against ncurses, and therefore -lncurses
+needs to be passed in addition to -lreadline.
+
+This proposal uses pkg-config when available. If pkg-config is not
+found, or readline is not found via pkg-config, we fallback to the
+existing AC_CHECK_LIB(). This AC_CHECK_LIB() test is modified to set
+READLINE_LIBS, like PKG_CHECK_MODULES() does. The Makefile.am
+consequently uses READLINE_LIBS instead of hardcoding -lreadline.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ configure.ac      | 14 ++++++++++++--
+ wrudf/Makefile.am |  2 +-
+ 2 files changed, 13 insertions(+), 3 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 95fbba3..62b1caa 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -9,8 +9,18 @@ AC_PROG_CC
+ AC_DISABLE_SHARED
+ AM_PROG_LIBTOOL
+ 
+-dnl Checks for libraries.
+-AC_CHECK_LIB(readline, readline, [ ], AC_MSG_ERROR([cannot find -lreadline.]))
++PKG_PROG_PKG_CONFIG
++
++dnl Checks for libraries, by using pkg-config when available
++if test -n "${PKG_CONFIG}" ; then
++  PKG_CHECK_MODULES([READLINE], [readline], [readline_found=yes], [readline_found=no])
++fi
++
++if test "${readline_found}" != "yes" ; then
++  AC_CHECK_LIB(readline, readline,
++               [AC_SUBST([READLINE_LIBS], [-lreadline])],
++               AC_MSG_ERROR([cannot find -lreadline.]))
++fi
+ 
+ dnl Checks for header files.
+ AC_HEADER_STDC
+diff --git a/wrudf/Makefile.am b/wrudf/Makefile.am
+index fe1c269..e3ab85b 100644
+--- a/wrudf/Makefile.am
++++ b/wrudf/Makefile.am
+@@ -1,5 +1,5 @@
+ bin_PROGRAMS = wrudf
+-wrudf_LDADD = $(top_builddir)/libudffs/libudffs.la -lreadline
++wrudf_LDADD = $(top_builddir)/libudffs/libudffs.la $(READLINE_LIBS)
+ wrudf_SOURCES = wrudf.c wrudf-cmnd.c wrudf-desc.c wrudf-cdrw.c wrudf-cdr.c ide-pc.c wrudf.h ide-pc.h ../include/ecma_167.h ../include/osta_udf.h ../include/bswap.h
+ 
+ AM_CPPFLAGS = -I$(top_srcdir)/include -D_GNU_SOURCE -DDEBUG
+-- 
+2.14.3
+

package/udftools/udftools.mk

@@ -8,6 +8,7 @@ UDFTOOLS_VERSION = 2.0
 UDFTOOLS_SITE = https://github.com/pali/udftools/releases/download/$(UDFTOOLS_VERSION)
 UDFTOOLS_LICENSE = GPL-2.0+
 UDFTOOLS_LICENSE_FILES = COPYING
-UDFTOOLS_DEPENDENCIES = readline
+UDFTOOLS_AUTORECONF = YES
+UDFTOOLS_DEPENDENCIES = readline host-pkgconf
 
 $(eval $(autotools-package))