autoconf-2.71 regression with intltool IT_PROG_INTLTOOL/AC_PROG_INTLTOOL macro

Hi,

AC_PROG_INTLTOOL stopped working if there is 'tab' on the beginning of
the line. See: https://issues.imfreedom.org/issue/PIDGIN-17509 for
details.

Actual results:
$ autoreconf -fi
libtoolize: putting auxiliary files in '.'.
libtoolize: copying file './ltmain.sh'
libtoolize: Consider adding 'AC_CONFIG_MACRO_DIRS([m4])' to configure.ac,
libtoolize: and rerunning libtoolize and aclocal.
libtoolize: Consider adding '-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
ERROR: 'IT_PROG_INTLTOOL' must appear in configure.ac for intltool to work.
autoreconf: error: intltoolize failed with exit status: 1

Expected results:
No error

Additional info:
It's failing because of the 'tab' before the AC_PROG_INTLTOOL. With
autoconf < 2.71 it doesn't fail. Maybe it's intltool bug, I don't
know, starting with the autoconf, because it breaks with the autoconf
update.

Ondrej