overflowed tick counter needs 64 bits everywhere

[dhalbert]

The 64-bit tick overflow counter was being truncated when copied, in certain cases.

This seems to fix #3919. It may also xxfix #3918, and perhaps xxfix #3912.

I still don't understand why this problem is showing up only in MacOS.

[tannewt]

Looks good to me! Thank you!

[dhalbert]

There is some other bug as well, that is present in 6.1.0-beta.3. Sleep times are too long and inaccurate now. Sounds like #3912.

Adafruit CircuitPython 6.0.1 on 2020-12-28; Adafruit Feather M0 Express with samd21g18
>>> import time
>>> print(time.monotonic()); time.sleep(0.1); print(time.monotonic())
14.036
14.136

But beta.3 is bad;

Adafruit CircuitPython 6.1.0-beta.3 on 2020-12-31; Adafruit Metro M0 Express with samd21g18
>>> import time
>>> print(time.monotonic()); time.sleep(0.1); print(time.monotonic())
19.724
20.851

Even with this PR:

Adafruit CircuitPython 6.1.0-rc.0-dirty on 2021-01-06; Adafruit Metro M0 Express with samd21g18
>>> import time
>>> print(time.monotonic()); time.sleep(0.1); print(time.monotonic())
11.315
12.383

[dhalbert]

I'm going to merge this fix now to fix #3919 and will backport it to 6.1.x before 6.1.0 final. We're still working on another sleep bug which is a second-order bug caused by a buffer overflow during a USB operation.