libffi: dlmmap fixes: race condition and PaX handling

[Stefan Bühler <stbuehler@web.de>]

Hi,

maybe this is of interest to you.

- https://github.com/libffi/libffi/pull/282
- opensuse pushed the patches to their devel:gcc/gcc5 Package:
  https://build.opensuse.org/request/show/427571

- Stefan