Spinlocks from spinlock.h do not disable the scheduler and thus cannot safely
be directly used as a locking mechanism. A task holding the lock can get
pre-empted, and at that point the new running task will also be allowed to
take the spinlock and access whatever it was protecting.
Another issue is that the task holding a spinlock could migrate to a different
core which in turn would cause the application to fail asserts. The current
implementation assumes the core that takes the lock is also the core that
releases it.
Closes https://github.com/espressif/esp-idf/issues/5762
- Introduce system time function and concept of system time provider.
esp_timer is system time provider when present.
- Set the reference point for system time, g_startup_time.
- Use the system time functions in newlib instead of calling esp_timer
functions directly
