Fix linker set macros to work with Mach-O object files.
Fix linker set macros to work with Mach-O object files.

twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc,twoporeguys/librpc