clang/wrapper cannot build GHC head with integer-gmp on Mavericks

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

Hi,

I'm try to make GHC head stably buildable with clang/wrapper on
Mavericks because we cannot ask all Mavericks users to install
apple-gcc or GCC.

The last big item for me is integer-gmp. GHC head cannot be built with
clang/wrapper if integer-gmp is used. (integer-simple is OK.)

This is because "configure" of libgmp fails. Now I understand why this
happens. The source of this problem is "/usr/bin/gcc" which is a
wrapper for clang (not gcc actually). This cheats "configure" of libgmp.

If we type "CC=clang ./configure", it works. The problem is how to
specify "CC=clang" to configure of libgmp when we build GHC head.  If
we modified "libraries/integer-gmp/gmp/ghc.mk" manually, we can build
GHC head. But I don't like this one since "make maintainer-clean"
removes "ghc.mk".

Any ideas?

Ticket is here:

	https://ghc.haskell.org/trac/ghc/ticket/8497

--Kazu