[CLI] Stop closing standard streams (v8.0)

[morrisonlevi]

Extensions may (and do) write to stderr in mshutdown and similar. In
the best case, with the stderr stream closed, it's just swallowed.

However, some libraries will do things like try to detect color, and
these will outright fail and cause an error path to be taken.

[morrisonlevi]

So our test runner doesn't check for non-zero exit codes. These four tests are failing on the PHP-8.0 branch with non-zero exit codes:

=====================================================================
FAILED TEST SUMMARY
---------------------------------------------------------------------
Bug #78376 (Incorrect preloading of constant static properties) [ext/opcache/tests/bug78376.phpt]
Bug #78175.2 (Preloading segfaults at preload time and at runtime) [ext/opcache/tests/bug78175_2.phpt]
Preloading inherited method with separated static vars [ext/opcache/tests/preload_method_static_vars.phpt]
Preload trait with static variables in method [ext/opcache/tests/preload_trait_static.phpt]
=====================================================================

They all print zend_mm_heap corrupted, but since stderr is closed at that time, it's not getting printed. All my patch does is allow us to see the message that it was already trying to print.

This shouldn't block this patch being merged, as it's merely uncovering a problem that already exists.

[arnaud-lb]

Merged in fa78e17