[llvm] r226473 - [AArch64] Implement GHC calling convention

[Tim Northover]

> Sorry to come late to the game, but this patch just got approved to land
> yesterday and the Haskell folks were hoping to see it in the 3.6 release.
> It implements the GHC Calling Convention for AArch64.  The functionality
> is nice and isolated - should be low risk!  Could you please pull it in?

Yep, looks pretty non-intrusive for 3.6 to me.

Tim.