[ODE] Slight patch for Mac OS X.3

[Shamyl Zakariya]

To whomever takes patches:

Mac OS X 10.3 *finally* introduced single precision trig functions, and 
as such the apple-specific #defines in Opcode.h cause linker errors.

I changed it from:

#if defined(__APPLE__) || defined(__MACOSX__)
#define sqrtf sqrt
#define sinf sin
#define cosf cos
#define acosf acos
#define asinf sinf
#endif

to:

#if defined(__APPLE__) || defined(__MACOSX__)
#if __APPLE_CC__ < 1495
#define sqrtf sqrt
#define sinf sin
#define cosf cos
#define acosf acos
#define asinf sinf
#endif
#endif

This way it builds happily on 10.2 and before, but will use 
single-precision on 10.3. Well, at least at build-time. I'm not certain 
about run-time. Right now, this is the only change I need to make to 
get ode-lib & opcode built happily. I use my own graphics system so I 
don't build drawstuff or any of the tests.

Also, one more thing. I don't want to suggest a patch here since I 
don't know how this affects other GNU type systems, but at least on Mac 
OS X, the opcode static library ( libopcode.a ) must have ranlib run on 
it before it can be linked into an executable. It would be easy to add 
that to the makefile, but I know Mac OS X has some oddities regarding 
binary formats compared to ELF systems like linux.

Shamyl Zakariya
   "this is, after all, one of those movies where people spend a great
   deal of time looking at things and pointing."
	From a review of _Fantastic Voyage_