bpo-45953: Statically initialize the small ints. (gh-30092)

bpo-45953: Statically initialize the small ints. (gh-30092)

The array of small PyLong objects has been statically declared. Here I also statically initialize them. Consequently they are no longer initialized dynamically during runtime init.

I've also moved them under a new sub-struct in _PyRuntimeState, in preparation for static allocation and initialization of other global objects.

https://bugs.python.org/issue45953