Log Message:
devel/ruby-ffi: update to 1.9.25

1.9.25 / 2018-06-03
-------------------

Changed:
* Revert closures via libffi.
  This re-adds ClosurePool and fixes compat with SELinux enabled systems. #621

1.9.24 / 2018-06-02
-------------------

Added:
* Added a CHANGELOG file
* Add mips64(eb) support, and mips r6 support. (#601)

Changed:
* Update libffi to latest changes on master.
* Don't search in hardcoded /usr paths on Windows.
* Don't treat Symbol args different to Strings in ffi_lib.
* Make sure size_t is defined in Thread.c. Fixes #609