This patch adds the tooling for incorporating files as C data, so that
files can be built into the binaries. The tool is in Python to avoid
adding extra dependencies like xxd.
xxd.py is copied from Mesa as-is, from commit
b729cd58d76f97f3fc04a67569535ee5ef2f5278 (master branch on 2021-01-26),
a.k.a 21.0-branchpoint-635-gb729cd58d76.
Moving the GLSL vertex shader into a separate file is not that
interesting, the purpose of this commit is to provide a simple
demonstration of the tooling. The real benefits come in a following
patch where the fragment shaders are re-written and externalized.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>