perf: run 'setup' function during stub run

perf: run 'setup' function during stub run

The benchmarked function might need the content of the setup to be run in order
to function properly.

--- a/contrib/perf.py	Fri Nov 23 02:08:01 2018 +0100
+++ b/contrib/perf.py	Thu Nov 22 23:48:44 2018 +0100
@@ -276,6 +276,8 @@
     return functools.partial(_timer, fm, displayall=displayall), fm
 
 def stub_timer(fm, func, setup=None, title=None):
+    if setup is not None:
+        setup()
     func()
 
 @contextlib.contextmanager