C++20 added std::source_location, which lets you capture the
callers __FILE__ / __LINE__ / __FUNCTION__ etc as a default
argument to functions.
See: https://en.cppreference.com/w/cpp/utility/source_location
During a bug investigation @ADKaster suggested we could use this
to make the LOCK_DEBUG feature of the kernel more user friendly
and allow it to automatically instrument all call sites.
We then implemented / tested it over discord. :^)
Co-Authored-by: Andrew Kaster <andrewdkaster@gmail.com>
