[openwrt/openwrt] lldpd: fix autoreconf failure

[LEDE Commits]

jow pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/dd5b3b58d8aa4427c40bc1247196a6693a57f460

commit dd5b3b58d8aa4427c40bc1247196a6693a57f460
Author: Jo-Philipp Wich <jo at mein.io>
AuthorDate: Wed Dec 9 11:53:04 2020 +0100

    lldpd: fix autoreconf failure
    
    The lldpd sources ship a modified local AX_LIB_READLINE M4 macro which
    conflicts with the official macro shipped by autoconf-archive.
    
    Due to the official macro having the same name and a higher serial
    number, autoconf will prefer including that one instead of the local
    copy, preventing the substitution of @READLINE_LIBS@ in Makefile.in
    templates, ultimately leading to the following build failure when
    linking lldpcli:
    
        ...-gcc: error: READLINE_LIBS@: No such file or directory
    
    Avoid this problem by renaming the locally shipped macro to not clash
    with the official implementation anymore.
    
    Ref: https://github.com/lldpd/lldpd/pull/423
    Acked-by: Stijn Tintel <stijn at linux-ipv6.be>
    Tested-by: Rosen Penev <rosenp at gmail.com>
    Signed-off-by: Jo-Philipp Wich <jo at mein.io>
---
 .../002-fix-AX_LIB_READLINE-macro-conflict.patch   | 61 ++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/package/network/services/lldpd/patches/002-fix-AX_LIB_READLINE-macro-conflict.patch b/package/network/services/lldpd/patches/002-fix-AX_LIB_READLINE-macro-conflict.patch
new file mode 100644
index 0000000000..9cdf66f2e7
--- /dev/null
+++ b/package/network/services/lldpd/patches/002-fix-AX_LIB_READLINE-macro-conflict.patch
@@ -0,0 +1,61 @@
+From 23509dc05b24a28fb46022800e0e271ae0118de2 Mon Sep 17 00:00:00 2001
+From: Jo-Philipp Wich <jo at mein.io>
+Date: Wed, 9 Dec 2020 12:04:04 +0100
+Subject: [PATCH] build: prevent conflict with official AX_LIB_READLINE macro
+
+On systems where the official AX_LIB_READLINE (ax_lib_readline.m4) is
+present in a globally shared autoconf include directory, auto(re)conf
+will prefer including that offical version over the local variant due
+to the offical macro having a higher serial number.
+
+As a consequence, @READLINE_LIBS@ will not be substituted in *.in files,
+eventually failing the compilation with errors similar to:
+
+    gcc: error: READLINE_LIBS@: No such file or directory
+
+Avoid this problem by renaming the incompatible local macro to
+AX_LIB_READLINE_LLDPD which is sufficient to prevent any clashes.
+
+We encountered this problem on OpenWrt which uses GNU autoconf-archive
+to provide commonly used M4 macros through a global include directory,
+which happens to ship AX_LIB_READLINE as well.
+
+Signed-off-by: Jo-Philipp Wich <jo at mein.io>
+---
+ configure.ac          | 2 +-
+ m4/ax_lib_readline.m4 | 6 +++---
+ 2 files changed, 4 insertions(+), 4 deletions(-)
+
+--- a/configure.ac
++++ b/configure.ac
+@@ -273,7 +273,7 @@ AC_ARG_WITH([readline],
+   [],
+   [with_readline=auto])
+ if test x"$with_readline" != x"no"; then
+-   AX_LIB_READLINE
++   AX_LIB_READLINE_LLDPD
+    if test x"$with_readline" != x"check" -a x"$with_readline" != x"auto"; then
+      if test x"$ax_cv_lib_readline" = x"no"; then
+        AC_MSG_FAILURE([*** no readline support found])
+--- a/m4/ax_lib_readline.m4
++++ b/m4/ax_lib_readline.m4
+@@ -4,7 +4,7 @@
+ #
+ # SYNOPSIS
+ #
+-#   AX_LIB_READLINE
++#   AX_LIB_READLINE_LLDPD
+ #
+ # DESCRIPTION
+ #
+@@ -66,8 +66,8 @@
+ 
+ #serial 6
+ 
+-AU_ALIAS([VL_LIB_READLINE], [AX_LIB_READLINE])
+-AC_DEFUN([AX_LIB_READLINE], [
++AU_ALIAS([VL_LIB_READLINE], [AX_LIB_READLINE_LLDPD])
++AC_DEFUN([AX_LIB_READLINE_LLDPD], [
+   AC_CACHE_CHECK([for a readline compatible library],
+                  ax_cv_lib_readline, [
+     _save_LIBS="$LIBS"