Issue #15977: Fix memory leak in Modules/_ssl.c when the function _set_npn_protocols() is called multiple times

(Compiler: Solaris Studio 12.3)

Required on Solaris 10 (which defines AT_FDCWD as 0xffd19553),
harmless on other platforms.

Patch by Jeremy Kloth.

Patch by Jeremy Kloth.

Issue #15842: the SocketIO.{readable,writable,seekable} methods now raise ValueError when the file-like object is closed.
Patch by Alessandro Moura.

Issue #15842: the SocketIO.{readable,writable,seekable} methods now raise ValueError when the file-like object is closed.
Patch by Alessandro Moura.

on the action's default, reverting it back to previous behavior.  Conversion
is only done on string defaults.

Add a test for this and another test that ensures such type conversions are
only called once.