[Bug target/63810] gcc sets incorrect macro for OS X deployment targets

[vq at larryv dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63810

--- Comment #31 from Lawrence Velázquez <vq at larryv dot me> ---
(In reply to mrs@gcc.gnu.org from comment #27)
> Fixed in 6.0. Backports pre approved after bake time and testing that
> includes older darwins and ppc.

Thanks! I've attached updated patches against 4.8, 4.9, and 5.1, if you need
them.