fsmonitor: normalize clock value to bytes

We normalize the value returned by watchman because
we perform a number of compares with this value in code.
So the easiest path forward is to normalize to bytes so we
don't have to update many call sites.

With this commit, the fsmonitor extension appears to be working
with Python 3! Although there are still some failures in edge
cases...

Differential Revision: https://phab.mercurial-scm.org/D7213

hgext/fsmonitor/__init__.py

@@ -383,7 +383,7 b' def overridewalk(orig, self, match, subr'
     else:
         # We need to propagate the last observed clock up so that we
         # can use it for our next query
-        state.setlastclock(result[b'clock'])
+        state.setlastclock(pycompat.sysbytes(result[b'clock']))
         if result[b'is_fresh_instance']:
             if state.walk_on_invalidate:
                 state.invalidate()