#9964: fix pdb failure to import under -OO. Warn the user that help is simply not available in this case.

`done` could be released multiple times because of concurrent
execution.  We convert it to an Event, where calling set()
multiple times is not a problem.

It looks like it is no more needed: Python 3.2 is slowly able to support
non-ascii paths with an ascii locale.

Python exits with a fatal error if the command line contains an undecodable
argument. PyUnicode_FromString() fails at the first undecodable byte because it
calls the error handler, but error handlers are not ready before Python
initialization.

the locale encoding.

don't do in configure as well.

Hopefully this will solve a Makefile parsing issue on the FreeBSD buildbots.

didn't match that of io.open(), and they also didn't get forwarded
properly to TextIOWrapper in text mode.  Patch by Kai Zhu.

for the OpenSSL server-side session cache.

urllib.request.urlopen now take optional arguments to allow for
server certificate checking, as recommended in public uses of HTTPS.