Always include <X11/Xfuncproto.h> for the definition of _X_NORETURN,
instead of relying on Xtrans.h to include it indirectly for us.
- Fixes: #2 (closed)
- Fixes: commit cc298d1f
Also includes CI changes to test builds both with and without xtrans to help catch issues like this before release next time, and to drop requirement for Signed-off-by tags in commits from our CI config, to match latest Xorg CI defaults.