Genie:  Simplify OpenMacFileHandle()
Genie:  Retry fsWrPerm as fsRdWrPerm for OS X 10.2

On Mac OS X 10.2.0 (Jaguar), if we pass fsWrPerm to FSpOpenDF(), permErr
is returned.  Retry with fsRdWrPerm.

This affects the Yellow box, not Classic, so leave non-Carbon unchanged.