Basically you are either going to want to configure and build with
--enable-maintainer-mode enabled, or else run "automake" by hand after
modifying the Makefile.am file.
It seems to me this maintainer mode is a stange beast. I have downloaded
and installed the four special packages from the binutils ftp-site. What
I want to do is simply to rebuild the regenerateable files from the
changes I've made (gas/Makefile.am in this case). Personally, I would
prefer to run make dep-am to ensure that the correct files are rebuilt.