GHC Port on 9-CURRENT

[b. f.]

>In any case, the port builds fine with GCC.  Perhaps it would be prudent
>to set CC=gcc and CXX=g++ in the makefile for the time being and mark
>the port as working again?

Please don't hardcode the compilers: users may be using other
compilers, or may still wish to experiment with clang, without having
to patch the port or override the Makefile.  Instead, if you feel it
is necessary, print a warning, or set IGNORE=... if clang or another
known bad compiler is chosen.

b.