[patch, libffi] Sync merge libffi

[Richard Kenner]

> My personal opinion is that it is better if open source software is not 
> encumbered by multiple copyright
> holders.  A copyright holder probably has the right to change the work's 
> permission notice.

Off-topic, but that works both ways: if you want to ensure that a
work's license's terms will never change, having a huge number of
copyright holders is one of the best ways to do that.