Enabling USB consumes a lot of power. So it's better to keep it disabled
by default when the serial port is set to something other than "usb"
(USB-CDC).
On my nice!nano clone, it reduces current consumption from 1mA to
0.13mA (and most of the rest is probably consumed by a connected SCD41
sensor).
This change might break some expectations, when a board uses USB but not
USB-CDC (I think this is rare, but I didn't check specifically).
Long sleep durations weren't implemented correctly, by simply casting to
a smaller number of bits. What we want is a saturating downcast, which
is what I've used here instead.
This should fix https://github.com/tinygo-org/tinygo/issues/3356.
Ayke van Laethem
Dan Kegel
Yurii Soldak
sago35