[MLton] Compiling mlton on MacOS

[John Reppy]

I have some time now to take another go at compiling mlton on MacOS X.  
I grabbed the latest sources
from CVS (I'm using SML/NJ 110.44) and I modified the Makefiles to 
properly use the LEX and YACC
variables, so when I run

	make LEX=ml-lex YACC=ml-yacc nj-mlton

I get a lot further, but I'm hitting the following error:

	...
	Unknown OS Darwin.
	ar rc libgdtoa.a gdtoa/*.o
	gcc -Wall -I. -Igdtoa -D_FILE_OFFSET_BITS=64 -fomit-frame-pointer -O2 
-c -o basis/Array/numElements.o basis/Array/numElements.c
	Unknown OS Darwin.
	In file included from basis/Array/numElements.c:2:
	mlton-basis.h:173:2: #error MLton_Rlimit_virtualMemorySize not defined
	make[2]: *** [basis/Array/numElements.o] Error 1
	make[1]: *** [runtime] Error 2
	make: *** [nj-mlton] Error 2

Any pointers on fixing this problem?  Thanks.

	- John