meson: Remove override_options asking for C++17 now it is the default
C++17 is now set as default option project-wide, so we don't need local overrides anymore.
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
C++17 is now set as default option project-wide, so we don't need local overrides anymore.