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
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown