__APPLE_CC__ defined on head of mainline

[Timothy J.Wood]

   I'm building the mainline (not the Apple branch) on Darwin and when I 
use the compiler, __APPLE_CC__ is defined.  I would have expected this 
to only be defined if using Apple's branch.  Is this desired behavior, 
or did the __APPLE_CC__ define accidentally get put in FSF's sources?

-tim