Now that we're generating the CMake toolchain file in the build
directory, we need to redirect the ports that use CMake to the new
location. Looking into this showed that there's still a bunch of work to
do in general to make the ports agnostic to which toolchain they're
using, there's a lot of hard-coded ${ARCH}-pc-serenity-gcc assumptions
still here.
The flatbuffers library is a serialization library, created by Google
for game development and performance-critical applications.
It aims to be fast and efficient.
This commit creates a port of it to SerenityOS.
The flatbuffers build process generates three things: some header files,
a library (libflatbuffers) and a schema compiler (flatc).
There are tests, but they are not compiled, because it runs the
flatbuffers schema compiler, one of the things we are cross-compiling.
The compiler will not run because the target is different from the host
