call.mod -> mercury_builtin.m

[Tyson Richard DOWD]

I'm intending to move call.mod into mercury_builtin.m, otherwise we get
some annoying warning messages from the linker. Any objections?

-- 
       Tyson Dowd           # 4.4: People keep saying the behavior is undefined,
                            # but I just tried it on an ANSI-conforming compiler
     trd at cs.mu.oz.au        # and got the results I expected.
http://www.cs.mu.oz.au/~trd # A: They were wrong. Flame them mercilessly. C-IAQ