missing: support AC_CONFIG_HEADERS in addition to obsolete AC_CONFIG_HEADER * missing (autoheader*): Do not look only for AC_CONFIG_HEADER when grepping configure.ac, but also for AC_CONFIG_HEADERS: the latter has been preferred to the former by several years now in Autoconf. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>