[tlbuild] problem disabling luajit and luatex

[Karl Berry]

            < LIBS =  -lm
            ---
            > LIBS = -lz -lm

I am not sure what to make of this.  The various programs that need libz
should be testing for it.  I can't think of why IA-64 should be
different.

(Since RH5 reaches end of life next year, it may not be worth any of
(y)our time to think about.)

k