Issue #19437: Fix _threading.RLock constructor (rlock_new), call

Py_DECREF(self) if PyThread_allocate_lock() failed instead of calling directly
type->tp_free(self), to keep the chained list of objects consistent when Python
is compiled in debug mode

fails, don't consume the row (restore it) and fail immediatly (don't call
pysqlite_step())