Run auto-spell-checker (codespell) on files in depot_tools.

This should only change spelling in:
 - messages that are printed
 - comments
 - docstrings

Review-Url: https://codereview.chromium.org/2277513002
diff --git a/gclient_scm.py b/gclient_scm.py
index 29079c5..fc17756 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -1647,7 +1647,7 @@
       self._RunAndGetFileList(['update', '--revision', 'BASE'], options,
           file_list)
     except OSError, e:
-      # Maybe the directory disapeared meanwhile. Do not throw an exception.
+      # Maybe the directory disappeared meanwhile. Do not throw an exception.
       logging.error('Failed to update:\n%s' % str(e))
 
   def revinfo(self, _options, _args, _file_list):