Apple's doc suggests using numerical values (e.g. 1090) rather than MAC_OS_X_VERSION_10_N because the symbol
may not be defined on earlier versions, causing the macro to work in odd ways. This is indeed what was
happening, so MAC_OS_X_VERSION_10_9 has been replaced with 1090 to allow building on earlier OS X systems.
[Details] Important: On Mavericks Tracks could be successfully built with static library linkage so far.
Use --internal-static-libs flag configuring the build.
[Reviewed by] Partially reviewed by Paul Davis. Some Improvements may be promoted in future.
