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: I08aa9e8e740c5f6506a76aaf5bea3402f97ac41a
Merge "Remove unneeded definitions of Python Source Code Encoding"