This is a workaround for the case where threading is enabled without a GIL.
In such a configuration, creating a new global variable is not atomic and
threads have race conditions resizing/accessing the global dict.
Signed-off-by: Damien George <damien@micropython.org>
Eg on PYBV10 with THREAD variant, the firmware has both the `_thread` and
`socket` modules but no NIC.
Signed-off-by: Damien George <damien@micropython.org>
