I am sorry, I do not know about tru64. Can you post me the output of make, eventually (no promise) I can point you into what needs to be changed. If we are lucky, its a minor thing...
hhmmmm... that puzzles me. gnu make should be able to process the linux makefile. The makefiles are not really platform-specific currently. There are just two of them, one for Linux and one for BSD. The reason for these two is to cover differences between gnu make and the default bsd make. Other than that, there is nothing platform specific in them (except for pathes etc which eventually need to be configured in Makefile and master.make). But again, I unfortunately have no idea what gmake complains about...