add_-latomic_to_ghc-prim

add_-latomic_to_ghc-prim

commit ce3897ffd6e7c8b8f36b8e920168bac8c7f836ae
Author: Ilias Tsitsimpis <iliastsi@debian.org>
Date:   Tue Sep 18 17:45:17 2018 +0200

    Fix check whether GCC supports __atomic_ builtins

    Summary:
    C11 atomics are never used because:

    * The program used for checking whether GCC supports
    __atomic_ builtins fails with the following error:

    ```
      error: size mismatch in argument 2 of `__atomic_load`
       int test(int *x) { int y; __atomic_load(&x, &y, __ATOMIC_SEQ_CST); return x; }
    ```

    * There is a typo when checking if CONF_GCC_SUPPORTS__ATOMICS equals YES,
    resulting in PRIM_CFLAGS and PRIM_EXTRA_LIBRARIES never being set.

    Reviewers: bgamari

    Reviewed By: bgamari

    Subscribers: rwbarton, erikd, carter

    Differential Revision: https://phabricator.haskell.org/D5154

Gbp-Pq: Name add_-latomic_to_ghc-prim