Don't try to call __log on a non-existent class

Signed-off-by: Adam D. Barratt <adam@adam-barratt.org.uk>

britney.py

@@ -342,7 +342,7 @@ class Britney:
         
         # integrity checks
         if self.options.nuninst_cache and self.options.print_uninst:
-            exit.__log("nuninst_cache and print_uninst are mutually exclusive!", type="E")
+            self.__log("nuninst_cache and print_uninst are mutually exclusive!", type="E")
             sys.exit(1)
         # if the configuration file exists, than read it and set the additional options
         elif not os.path.isfile(self.options.config):