update requested, tested, and ok by rsadowski@
rsadowski@ helped with WANTLIB update, cmake options, and vulkan-hpp patch
also tested by me briefly including in-game gameplay without issues.
note on my testing OpenGL backend is still the default on amd64 with intel
GPU. I can't find documentation on a switch to enable Vulkan backend yet.
Best place to view changelogs is the Hard Light fs2open forums:
https://www.hard-light.net/forums/index.php?board=50.0
Upstream isn't packaging source tarballs anymore, so now using GH with
the cmake module and librocket pulled in additionally similar to what
emulators/ppsspp and other ports do.
32ad89751c