Compiling on OS-X jaguar

Can anyone tell me what to use for the OS type when compiling on OS-X 
10.2.4?  Using ./configure osx doesn't work, not recognized.  The output of 
uname on this machine is:

Darwin mapfinder2 6.4 Darwin Kernel Version 6.4: Wed Jan 29 18:50:42 PST 
2003; root:xnu/xnu-344.26.obj~1/RELEASE_PPC  Power Macintosh powerpc

If I try using ./build osx it fails here:

logwtmp.c:154: `O_WRONLY' undeclared (first use in this function)

I've tried cc or gcc wth no luck.  Any ideas would be appreciated.

-Mike