[3.12] gh-112716: Fix SystemError when __builtins__ is not a dict (GH-112770) (GH-113103)

It was raised in two cases:
* in the import statement when looking up __import__
* in pickling some builtin type when looking up built-ins iter, getattr, etc.

(cherry picked from commit 1161c14e8c68296fc465cd48970b32be9bee012e)