Added additional tests for expat parser attributes.
Based on patch by John Leitch.

Windows.  The test now makes sense on non-Windows.  Added similar test for
zip format.

details in issue25018.

there (as when opening Idle from interactive Python on Windows).

Patch from John Beck.

Patch from Matheus Vieira Portela.

in an infinite loop.  Patch by Xavier de Gaye.

Issue #24891: Fix a race condition at Python startup if the file descriptor
of stdin (0), stdout (1) or stderr (2) is closed while Python is creating
sys.stdin, sys.stdout and sys.stderr objects. These attributes are now set
to None if the creation of the object failed, instead of raising an OSError
exception. Initial patch written by Marco Paolini.

The ICC compiler doesn't seem to support defined() in macro expansion. Example
of warning:

warning #3199: "defined" is always false in a macro expansion in Microsoft mode

BaseTest now ensures that unittest.TestCase.assertWarns() uses the same
warnings module than warnings.catch_warnings(). Otherwise,
warnings.catch_warnings() will be unable to remove the added filter.

when the test is interrupted (or fail).

Mention also the detected GDB version on verbose mode and on error (if the
major version is smaller than 7).

Patch from Mattip.

Patch from Berker Peksag.

Patch by tagatac

Patch by Mark Roseman.

Patch by Joseph Weston.

Patch from Pam McA'Nulty.

Patch by Ethan Furman.