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: I3f3d56b28001e2b27a4a749ecc9b3ac1c80a5b5c
Merge "Remove unneeded definitions of Python Source Code Encoding"