The best_effort_wfe_or_timeout() and sleep_us() pico-sdk functions use the
pico-sdk alarm pool internally, and that has a bug.
Some usages inside pico-sdk (notably multicore_lockout_start_blocking())
will still end up calling best_effort_wfe_or_timeout(), although usually
with "end_of_time" as the timeout value so it should avoid any alarm pool
race conditions.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
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