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: I6e3646e7e8882d784c82055e223e763fb3a3eb50
Merge "Remove unneeded definitions of Python Source Code Encoding"