fix doctest calling configLogger causing flakiness of other tests

since we use pytest-randomly to randomize the test execution, depending on when
this specific test is executed, it may have the side effect of configuring
the global logging configuration, causing other tests that capture logging
messages to fail.

E.g. see https://travis-ci.org/fonttools/fonttools/jobs/545680550
diff --git a/Lib/fontTools/misc/loggingTools.py b/Lib/fontTools/misc/loggingTools.py
index b00fff0..b4b9a9b 100644
--- a/Lib/fontTools/misc/loggingTools.py
+++ b/Lib/fontTools/misc/loggingTools.py
@@ -250,8 +250,8 @@
 	upon exiting the with-statement.
 
 	>>> import logging
-	>>> log = logging.getLogger("fontTools")
-	>>> configLogger(level="DEBUG", format="%(message)s", stream=sys.stdout)
+	>>> log = logging.getLogger("my-fancy-timer-logger")
+	>>> configLogger(logger=log, level="DEBUG", format="%(message)s", stream=sys.stdout)
 	>>> with Timer(log, 'do something'):
 	...     time.sleep(0.01)
 	Took ... to do something