_create_tmp_config_dir() "mkdirs" the returned dir

Fixes matplotlib#4120

Author: Eugen Beck

lib/matplotlib/__init__.py

@@ -537,6 +537,7 @@ def _create_tmp_config_dir():
     """
     import getpass
     import tempfile
+    from matplotlib.cbook import mkdirs
 
     try:
         tempdir = tempfile.gettempdir()
@@ -547,6 +548,11 @@ def _create_tmp_config_dir():
     tempdir = os.path.join(tempdir, 'matplotlib-%s' % getpass.getuser())
     os.environ['MPLCONFIGDIR'] = tempdir
 
+    try:
+        mkdirs(tempdir)
+    except OSError:
+        pass
+
     return tempdir