package/lldpd: disable use of libbsd

libbsd installs at least one .pc file that contains a -isystem include
path (-isystem /usr.include/bsd), but -isystem is not munged by
pkg-config, so we end up using /usr/include/bsd which is not suitable
for the target. And breaks big time (see failures, below).

But using libbsd is completely optional. In fact, our lldpd.mk did not
even express the dependency on libbsd, so we may well have had builds
without libbsd.

The functionality brought in by using libbsd is very minor (just setting
the neighbour name in /proc/self/cmdline), so we just make lldpd not use
libbsd at all. There is no --disable-libbsd or such, so we just patch it
out of configure.ac.

Fixes:
    http://autobuild.buildroot.org/results/6b7/6b70fa379e834ec71cc260ba6af771b531ca3511/
    http://autobuild.buildroot.org/results/769/769074c4bb67336ae6679f2c1cd2a8220d2bec24/
    http://autobuild.buildroot.org/results/c8a/c8a6001f437701ecc75f6c9252935645bda8a8c8/
    [...]

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lldpd/0002-configure-do-not-check-for-libbsd.patch

@@ -0,0 +1,61 @@
+From 0801a066cd4a24a858ddfa7c62c7802e0f5533a8 Mon Sep 17 00:00:00 2001
+From: "Yann E. MORIN" <yann.morin.1998@free.fr>
+Date: Sun, 14 Aug 2016 12:15:17 +0200
+Subject: [PATCH] configure: do not check for libbsd
+
+libbsd causes build issues because its libbsd-overlay.pc file is borked:
+it contains -isystem in CFLAGS, which is not munged by pkgconf, so we
+end up using the headers of the build machine, causing all sorts of
+hard-to-debug trouble at build time.
+
+lldpd uses libbsd-overlay for a few helper functions, but has fallbacks
+in case it is not available. The only feature that is lost when not using
+it is that the neighbour name is no longer displayed in /proc/self/cmdline.
+As the author of lldpd said on IRC: "people should survive! ;-)"
+
+So we just remove the detection of libbsd altogether.
+
+Fixes:
+    http://autobuild.buildroot.org/results/6b7/6b70fa379e834ec71cc260ba6af771b531ca3511/
+    http://autobuild.buildroot.org/results/769/769074c4bb67336ae6679f2c1cd2a8220d2bec24/
+    http://autobuild.buildroot.org/results/c8a/c8a6001f437701ecc75f6c9252935645bda8a8c8/
+    [...]
+
+Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
+---
+ configure.ac | 19 -------------------
+ 1 file changed, 19 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index dd723b0..45498ce 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -165,25 +165,6 @@ AC_FUNC_MALLOC
+ AC_FUNC_REALLOC
+ AC_FUNC_FORK
+ 
+-# Some functions can be in libbsd
+-PKG_CHECK_MODULES([libbsd], [libbsd-overlay], [
+-  _save_CFLAGS="$CFLAGS"
+-  _save_LIBS="$LIBS"
+-  CFLAGS="$CFLAGS $libbsd_CFLAGS"
+-  LIBS="$LIBS $libbsd_LIBS"
+-  AC_MSG_CHECKING([if libbsd can be linked correctly])
+-  AC_LINK_IFELSE([AC_LANG_SOURCE([[int main() { return 0; }]])],
+-    [
+-      AC_MSG_RESULT(yes)
+-      LLDP_CFLAGS="$LLDP_CFLAGS $libbsd_CFLAGS"
+-      LLDP_LDFLAGS="$LLDP_LDFLAGS $libbsd_LIBS"
+-    ],[
+-      AC_MSG_RESULT(no)
+-      CFLAGS="$_save_CFLAGS"
+-      LIBS="$_save_LIBS"
+-    ])
+-], [:])
+-
+ # setproctitle may have an _init function
+ AC_REPLACE_FUNCS([setproctitle])
+ AC_CHECK_FUNCS([setproctitle_init])
+-- 
+2.7.4
+

package/lldpd/lldpd.mk

@@ -9,7 +9,7 @@ LLDPD_SITE = http://media.luffy.cx/files/lldpd
 LLDPD_DEPENDENCIES = host-pkgconf libevent
 LLDPD_LICENSE = ISC
 LLDPD_LICENSE_FILES = README.md
-# 0001-build-make-generation-of-atom-glue-compatible-with-o.patch
+# 0002-configure-do-not-check-for-libbsd.patch
 LLDPD_AUTORECONF = YES
 
 ifeq ($(BR2_PACKAGE_CHECK),y)