Turns out the scheduler isn't always disabled while timer callbacks
are invoked depending on the version. Given the minimal cost this
change goes ahead and always locks the scheduler.
No-Docs-Update-Reason: No API change.
Change-Id: I8a4dc5945bf35dc7eadf3fa379ebfd4755a30639
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/52565
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Kevin Zeng <zengk@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>
Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com>