Switch from using debug_control structure to debug_named_value structure. The main nice feature is that it provides a "help" option, so using "V3D_DEBUG=help" will print all the debug options with a brief description. Useful to avoid going to https://docs.mesa3d.org/envvars.html everytime we need to know the available options. v1: - Modify a couple of debug option documentation (Alejandro) Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com> Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12036>