[Python-Dev] Implementation of the PEP 433

[Victor Stinner]

I created the following issue to track and review the implementation
of the PEP 433:
http://bugs.python.org/issue17036

Last changes:
 - don't hold the GIL to ensure "atomicity" of the close-on-exec flag
 - apply the default value of cloexec on all C functions
 - sys.setdefaultcloexec() don't have any argument anymore (unit tests
don't use sys.setdefaultcloexec() anymore)

Victor