Aiming for a libffi release in the next two weeks

[Anthony Green]

DJ brought to my attention the fact that we'll be missing important release
windows for Fedora and downstream distros if we don't get something out the
door in the next two weeks.  And I'm very excited about the improvements
targeted for this release -- Madhavan's static trampoline work in
particular.

There are a number of PR and Issues that have been sitting around for a
while.  Please bump them if you think they are important.

One area I'd like some clarity on is "apple silicon" support.  Not being a
Mac user, I'm looking at Apple and Jeremy Huddleston Sequoia for guidance
here.  There's a big PR WIP sitting on github.

Also.. travis-ci testing for MacOS hasn't been working for a long time
thanks to homebrew timeouts.  Something got really slow here.   Does
anybody have insight into this?

As always, thank you for your contributions and patience.  Big shout out to
DJ for his recent efforts.

AG

In the queue for 3.4...

        Add static trampoline support for Linux on x86_64 and ARM64.
        Add support for Alibaba's CSKY architecture.
        Add support for Kalray's KVX architecture.
        Add support for Intel Control-flow Enforcement Technology (CET).
        Add support for ARM Pointer Authentication (PA).
        Fix 32-bit PPC regression.
        Fix MIPS soft-float problem.
        Fox x86-64 nested struct varargs passing problem.
        Enable tmpdir override with the $LIBFFI_TMPDIR environment variable.
        Enable compatibility with MSVC runtime stack checking.
        Reject float and small integer argument in ffi_prep_cif_var().
          Callers must promote these types themselves.