automake 1.11.1 does not support AM_PROG_AR macr

Issue

• In trying to compile log4cxx from source, the automake run failed due to the AM_PROG_AR macro not being present in that version of automake.

$ automake --version
automake (GNU automake) 1.11.1
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl-2.0.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Tom Tromey <tromey@redhat.com>
       and Alexandre Duret-Lutz <adl@gnu.org>.
$ svn co http://svn.apache.org/repos/asf/incubator/log4cxx/trunk
$ cd trunk
$ ./autogen.sh
configure.ac:47: warning: macro `AM_PROG_AR' not found in library
configure.ac:47: error: possibly undefined macro: AM_PROG_AR
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.