buildman: Update tests for newer filelock module

Recent versions of this module call time.perf_counter() so add a patch
for this also.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Tom Rini <trini@konsulko.com>

tools/buildman/test.py

@@ -836,6 +836,7 @@ class TestBuild(unittest.TestCase):
         tmpdir = self.base_dir
 
         with (patch('time.time', side_effect=self.get_time),
+              patch('time.perf_counter', side_effect=self.get_time),
               patch('time.monotonic', side_effect=self.get_time),
               patch('time.sleep', side_effect=self.inc_time),
               patch('os.kill', side_effect=self.kill)):