Updated: protobuf-21.12-2

[ASSI]

This is a re-release of the latest upstream bugfix release of protobuf
21.12 with patches backported from newwer releases by Debian to fix
various security issues.

Protocol Buffers (a.k.a., protobuf) are Google's language-neutral,
platform-neutral, extensible mechanism for serializing structured data.


Note
====

Upstream changed their version numbering scheme to omit the leading
"3." from their releases (the internal version number still uses the old
versioning scheme, though).

Upstream does not support Cygwin officially and this is the last version
that does not have dependencies that are not building on Cygwin.  No
further updates will be possible until someone ports at least those
portions of Abseil to Cygwin that are used by protobuf.