tests: disable test-nointerrupt on Windows

Per the followup discussion[1].  proc.send_signal(INT) in timeout.py raises a
ValueError because of an unsupported signal.  I don't like missing test coverage
for this on Windows.  But this is the last test failing on Windows, and red all
the time hides new failures.

[1] https://phab.mercurial-scm.org/D3716

tests/test-nointerrupt.t

@@ -1,3 +1,5 b''
+#require no-windows
+
 Dummy extension simulating unsafe long running command
   $ cat > sleepext.py <<EOF
   > import itertools