Remove unneeded definitions of Python Source Code Encoding

PEP 0263 (http://legacy.python.org/dev/peps/pep-0263/) is not
used anywhere else and should be removed when it's not needed.

Change-Id: I8e2893b186121beb09cb6fd17d2c9c10aaa18008
Merge "Remove unneeded definitions of Python Source Code Encoding"