Under Mac OS 10.5.8, I fully confirm the issue described above by Joe Shirk :
'gdisk' systematically fails with following error message :
dyld: unknown required load command 0x80000022
As a solution, I suggest you to set the 'MACOSX_DEPLOYMENT_TARGET' environment variable to '10.5' just before your link command, as described in :
Thank you in advance for your work.