The newer function names are not available until Mac OS X 10.6.0.

However, the newer function names are just a simple rename of the
older functions with exactly the same arguments.

If the build target is prior to Mac OS X 10.6.0 (where the new
function names became available) add a few backwards compatibility
defines to allow the source to build on older Mac OS X versions.

Newer systems will continue to use the new names and avoid the
ugly deprecation warnings while builds for older systems will
just work.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>