[New] devel/flatbuffers

Hello,

Please see attached for a new port: flatbuffers
(https://google.github.io/flatbuffers/).

Quoting the homepage:

"FlatBuffers is an efficient cross platform serialization library for
C++, C#, C, Go, Java, Kotlin, JavaScript, Lobster, Lua, TypeScript, PHP,
Python, Rust and Swift. It was originally created at Google for game
development and other performance-critical applications."

The attached port builds and passes the test suite. The package installs
and appears to work as indended. Portcheck reports clean. There is a
patch included which fixes some include issues (similar to what's seen
in the chromium and irdium ports - which include flatbuffers as an
in-repo dependency). There is already a similar patch in upstream's
queue which should land soon.

Comments and feedback appreciated.

Thanks,

Ash