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/fix_encoding.py b/fix_encoding.py
index 107ca6c..a086af3 100644
--- a/fix_encoding.py
+++ b/fix_encoding.py
@@ -356,7 +356,7 @@
 def fix_encoding():
   """Fixes various encoding problems on all platforms.
 
-  Should be called at the very begining of the process.
+  Should be called at the very beginning of the process.
   """
   ret = True
   if sys.platform == 'win32':