gh-125900: Clean-up logic around immortalization in free-threading (#125901)

* Remove `@suppress_immortalization` decorator
* Make suppression flag per-thread instead of per-interpreter
* Suppress immortalization in `eval()` to avoid refleaks in three tests
  (test_datetime.test_roundtrip, test_logging.test_config8_ok, and
   test_random.test_after_fork).
* frozenset() is constant, but not a singleton. When run multiple times,
  the test could fail due to constant interning.

1 files changed, 0 insertions, 8 deletions

diff --git a/Include/internal/pycore_gc.h b/Include/internal/pycore_gc.h
index cf96f66..b85957d 100644
--- a/Include/internal/pycore_gc.h
+++ b/Include/internal/pycore_gc.h
@@ -342,14 +342,6 @@ struct _gc_runtime_state {
        collections, and are awaiting to undergo a full collection for
        the first time. */
     Py_ssize_t long_lived_pending;
-
-    /* gh-117783: Deferred reference counting is not fully implemented yet, so
-       as a temporary measure we treat objects using deferred reference
-       counting as immortal. The value may be zero, one, or a negative number:
-        0: immortalize deferred RC objects once the first thread is created
-        1: immortalize all deferred RC objects immediately
-        <0: suppressed; don't immortalize objects */
-    int immortalize;
 #endif
 };