Now that standard exceptions are builtin, we don't need two phase init

or fini of the builtin module.

_PyBuiltin_Init_1 => _PyBuiltin_Init
_PyBuiltin_Init_2 removed
_PyBuiltin_Fini_1 removed
_PyBuiltin_Fini_2 removed

These functions are used to initialize the _exceptions module.

init_exceptions added
fini_exceptions added