bpo-35441: Remove dead and buggy code related to PyList_SetItem(). (GH-11033)

In _localemodule.c and selectmodule.c, remove dead code that would
cause double decrefs if run.

In addition, replace PyList_SetItem() with PyList_SET_ITEM() in cases
where a new list is populated and there is no possibility of an error.

In addition, check if the list changed size in the loop in array_array_fromlist().
(cherry picked from commit 99d56b5356)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Python/ceval.c

@@ -5056,7 +5056,7 @@ getarray(long a[256])
             Py_DECREF(l);
             return NULL;
         }
-        PyList_SetItem(l, i, x);
+        PyList_SET_ITEM(l, i, x);
     }
     for (i = 0; i < 256; i++)
         a[i] = 0;
@@ -5078,7 +5078,7 @@ _Py_GetDXProfile(PyObject *self, PyObject *args)
             Py_DECREF(l);
             return NULL;
         }
-        PyList_SetItem(l, i, x);
+        PyList_SET_ITEM(l, i, x);
     }
     return l;
 #endif

Python/sysmodule.c

@@ -2544,7 +2544,7 @@ makepathobject(const wchar_t *path, wchar_t delim)
             Py_DECREF(v);
             return NULL;
         }
-        PyList_SetItem(v, i, w);
+        PyList_SET_ITEM(v, i, w);
         if (*p == '\0')
             break;
         path = p+1;