This can lead to duplicate initialisations if a module can be imported
via multiple names, so the module must track this itself anyway.
This reduces code size (diff is -40 bytes), and avoids special treatment of
builtin-modules-with-init with respect to sys.modules. No other builtin
modules get put into sys.modules.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>