Top-level make fails in UDF autoreconf with Automake 1.13

With Automake 1.13 (which is the default version on e.g. Ubuntu 13.10), top-level Make results in:

...
cd "Percona-Server-5.1.72-rel14.10"/UDF && autoreconf --install
libtoolize: Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
libtoolize: rerunning libtoolize, to keep the correct libtool macros in-tree.
libtoolize: Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
libtoolize: `AC_PROG_RANLIB' is rendered obsolete by `LT_INIT'
automake: warnings are treated as errors
/usr/share/automake-1.13/am/ltlibrary.am: warning: 'libfnv1a_udf.la': linking libtool libraries using a non-POSIX
/usr/share/automake-1.13/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'
src/Makefile.am:1: while processing Libtool library 'libfnv1a_udf.la'
/usr/share/automake-1.13/am/ltlibrary.am: warning: 'libfnv_udf.la': linking libtool libraries using a non-POSIX
/usr/share/automake-1.13/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'
src/Makefile.am:1: while processing Libtool library 'libfnv_udf.la'
/usr/share/automake-1.13/am/ltlibrary.am: warning: 'libmurmur_udf.la': linking libtool libraries using a non-POSIX
/usr/share/automake-1.13/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'
src/Makefile.am:1: while processing Libtool library 'libmurmur_udf.la'
autoreconf: automake failed with exit status: 1
make: *** [maatkit-udf] Error 1

http://jenkins.percona.com/job/percona-server-5.1-trunk/723/BUILD_TYPE=release,Host=ubuntu-saucy-64bit/console

This issue is already prevented (or fixed) in 5.5 and 5.6 trees, where configure.ac has extra line
m4_ifdef([AM_PROG_AR], [AM_PROG_AR])

(Just adding AM_PROG_AR will not work, as this macro is undefined in earlier Automake versions).

We should add this to 5.1 too. There are other ways to fix this (disable Automake -Werror or -Wextra-portability), but probably the best idea is to backport the 5.5/5.6 fix.