[parrot/parrot] 50dcc6: [configure] Improve auto::libffi probe

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/parrot/parrot
  Commit: 50dcc67d2bbcca657e601080ba752d428377d3bd
      https://github.com/parrot/parrot/commit/50dcc67d2bbcca657e601080ba752d428377d3bd
  Author: Pascal Stumpf <Pascal.Stumpf at cubes.de>
  Date:   2014-01-27 (Mon, 27 Jan 2014)

  Changed paths:
    M config/auto/libffi/test_c.in

  Log Message:
  -----------
  [configure] Improve auto::libffi probe

Apply patch by pstumpf [GH #1030] to fix a failing probe
with -fstack-protector-all or -fstack-protector-strong with
recent GCC and OpenBSD’s toolchain.
Analysed by Martynas Venckus.