build: resolve automake-1.12 warnings

am/ltlibrary.am: warning: 'libnetfilter_queue.la': linking libtool
libraries using a non-POSIX archiver requires 'AM_PROG_AR' in
'configure.ac'

Signed-off-by: Jan Engelhardt <jengelh@inai.de>

diff --git a/configure.ac b/configure.ac
index 0a1fbd6..07747a6 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -8,6 +8,7 @@ AC_CONFIG_HEADERS([config.h])
 
 AM_INIT_AUTOMAKE([-Wall foreign subdir-objects
        tar-pax no-dist-gzip dist-bzip2 1.6])
+m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
 
 dnl kernel style compile messages
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])