Use idiomatic way to tell Autoconf the c compiler

The non-idiomatic `--with-cc` flag was added via
5c789e424c1461c1dadfd38c44fcb9e8f38bf755

However, `--with-cc` seems rather fragile and support for `--with-cc` needs
to be added explicitly to autoconf-based Cabal packages. The `CC=` flag, however,
is supported natively by GNU Autoconf, so let's use the standard facility for that.

Relatedly, Cabal prior to version 1.24 used a similiar flag `--with-gcc=...`,
but starting with Cabal-1.24 this has been changed to use `CC=...` instead as well
(see https://github.com/haskell/cabal/pull/2946)

This also updates a few submodules removing the now obsolete `--with-cc` flag
support.

Reviewed By: trofi, thomie, erikd

Differential Revision: https://phabricator.haskell.org/D1608

1 files changed, 0 insertions, 0 deletions

diff --git a/libraries/unix b/libraries/unix
-Subproject 147630c7c76bd9b947524ef140d21b9e81967c6
+Subproject 59edb0a0a0d91ecfe938029b3b00a0c99dcb848