fsmonitor: refresh pywatchman to upstream
Update to upstream to version c77452. The refresh includes fixes to improve
windows compatibility.
There is a minor update to 'test-check-py3-compat.t' as c77452 no longer have
the py3 compatibility issues the previous version had.
# no-check-commit
% creating repo
% add and commit
C test.py
% change
M test.py