In #4683, tannewt noticed that uncrustify was not running on some
file in common-hal.
I investigated and found that it was not being run on a bunch of paths.
Rather than make incremental changes, I rewrote list_files to work
bsaed on regular expressions; these regular expressions are created from
the same git-style glob patterns.
I spot-checked some specific filenames after this change, and all looks good:
```
$ python3 tools/codeformat.py -v --dry-run tests/basics/int_small.py ports/raspberrypi/common-hal/pulseio/PulseIn.c extmod/virtpin.c tests/thread/thread_exit1.py ports/raspberrypi/background.h extmod/re1.5/recursiveloop.c
tools/codeformat.py -v --dry-run tests/basics/int_small.py ports/raspberrypi/common-hal/pulseio/PulseIn.c extmod/virtpin.c tests/thread/thread_exit1.py ports/raspberrypi/background.h extmod/re1.5/recursiveloop.c
uncrustify -c /home/jepler/src/circuitpython/tools/uncrustify.cfg -lC --no-backup extmod/virtpin.c ports/raspberrypi/background.h ports/raspberrypi/common-hal/pulseio/PulseIn.c
black --fast --line-length=99 -v tests/thread/thread_exit1.py
```
recursiveloop and int_small are excluded, while PulseIn, virtpin,
and background are included.
Testing running from a subdirectory (not _specifically_ supported though):
```
(cd ports && python3 ../tools/codeformat.py -v --dry-run raspberrypi/common-hal/pulseio/PulseIn.c ../extmod/virtpin.c)
../tools/codeformat.py -v --dry-run raspberrypi/common-hal/pulseio/PulseIn.c ../extmod/virtpin.c
uncrustify -c /home/jepler/src/circuitpython/tools/uncrustify.cfg -lC --no-backup ../extmod/virtpin.c raspberrypi/common-hal/pulseio/PulseIn.
```
As a side-effect, a bunch more files are re-formatted now. :-P
We now track the last time the background task ran and bail on the
PulseIn if it starves the background work. In practice, this
happens after the numbers from pulsein are no longer accurate.
This also adjusts interrupt priorities so most are the lowest level
except for the tick and USB interrupts.
Fixes#516 and #876
Jeff Epler
root
Scott Shawcroft
Scott Shawcroft