Fix issue 13370: Ensure that ctypes works on Mac OS X when Python is compiled using the clang compiler

Patch by Chris Rebert.

Closes #9374: add back now-unused module attributes; removing them is a backward compatibility issue, since they have a public-seeming name.

Fix by Colin Su.  Test by me, based on a test written by Petri Lehtinen.

It was exposed by 03c98d05b140 and dbbf3ccf72e8.

(Patch by Ronald Oussoren)

This is due to an off-by-one error: the allocated buffer didn't have room for a NUL
character at the end of the mbstowcs result.

This is necessary for ZFS systems, which don't support UF_IMMUTABLE.

Patch by Ethan Furman.

Suggestion and patch by Mike Hoy.

Patch by Robin Schreiber.

Found by Coverity.

Patch by Francisco Martín Brugué.

for certain locales (utf-16 and utf-32 family).

Patch by Chris Jerdonek.

Patch by Kushal Das.

Patch by Chris Jerdonek.

This is analogous to the link for `flie objects` in the description of
'open' that exists in the 2.7 docs, and adds a similar link to the
io docs.

Patch by Chris Jerdonek.

Update the getpeercert() example with a real-world cert showing non-trivial issuer, subject and subjectAltName.

When adding a message from a binary file, \r\n was translated to
\r\r\n in the message body.