clang warnings

[Kazu Yamamoto (=?iso-2022-jp?B?GyRCOzNLXE9CSScbKEI=?=)]

Austin,

> I've already merged two changesets into 7.8.3 -
> https://github.com/ghc/ghc/commit/52222f9e0bedc9b08b46619f8ed4d09f645d6ed4
> and https://github.com/ghc/ghc/commit/fd4169f9caf6922e3e5ea9c31f497f7220fc62b8
> - which add -Qunused-arguments to the C compiler invocation if the
> compiler is Clang. The GHC but is #9047
> 
> (The problem was Clang will ignore a lot of the flags we pass in the
> assembler stage, since it will be used as the assembler). So I don't
> think a workaround will be needed.

Great.

I confirmed that I can validate both GHC HEAD and the ghc-7.8 branch
on Mac WITHOUT ghc-clang-wrapper.

--Kazu