ports Makefile malformed conditional in XFree86-4

[esmith]

Trying to build xfree86-4 today, on a newly installed system, produces a 
failure. Neither make nor gmake would process the Makefile properly. 
Native make reports:

XFree86-4.3.0,1 depends on shared library X11.6 - not found
. ..
"Makefile", line 63: Malformed conditional (${X_WINDOW_SYSTEM:L} != 
xfree86-4)
"Makefile", line 65: if-less endif
"Makefile", line 65: Needs an operator
fatal errors encountered

The library X11.6 does not exist on the system.
Any suggestions are welcome.