Hmm, again, this probably won't help but on the 3 *nix machines I have available to me:
os x (with X installed): /usr/X11R6/bin/makedepend
openbsd (no X): not found
ubuntu (with X obviously): /usr/X11R6/bin/makedepend
I don't know much about it, but from my brief peak at the manpage I don't understand why this is an X-only thing
