This ensures all test output is properly captured, avoids potential
bugs in Vulkan libraries, drivers, and layers if multiple Vulkan instances
are created and destroyed by different threads, allows for tests to be
skipped at runtime if prerequisites do not hold, and will make it possible
in the future to test different builds of Waypipe against each other.

The cost is a lot of extra build and test framework complexity.

And fix a test sending incorrect Wayland messages.

This saves >20 core-seconds of build time and 140MB of build space;
bindgen is commonly packaged and easy to install via cargo.

Version 1.77.0 provides C-string literals which, while not strictly
necessary, do make the FFI code simpler.

As waypipe-c is included in the repository, users of older systems
which do not have recent Rust have a fallback.