How to best reference ltdl.m4?

[Zopolis0]

As part of my gcj work, I need to call a couple of variables and functions
from ltdl.m4 (installed in usr/share/aclocal, as part of libltdl).

Should I reference the system installed copy? How would I do that?

Or should I copy it into the gcc root directory, like what was done with
libtool.m4? If I end up doing that, what version should I use? (2.2.6 to
match the other files, or the latest version, or update all the files)