bpo-30074: Fix compile warnings of _PySlice_Unpack and convert missed (#1154)

PySlice_GetIndicesEx in _ctypes.c.
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 8c17245..72f2ad8 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -435,7 +435,7 @@
     }
     else if (PySlice_Check(index)) {
         Py_ssize_t start, stop, step, slicelength, cur, i;
-        if (_PySlice_Unpack((PySliceObject *)index, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(index, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(PyByteArray_GET_SIZE(self),
@@ -619,7 +619,7 @@
         }
     }
     else if (PySlice_Check(index)) {
-        if (_PySlice_Unpack((PySliceObject *)index, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(index, &start, &stop, &step) < 0) {
             return -1;
         }
         slicelen = _PySlice_AdjustIndices(PyByteArray_GET_SIZE(self), &start,
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 24bb5bb..bb65e98 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2562,7 +2562,7 @@
         PyObject* it;
         PyObject **src, **dest;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
@@ -2612,7 +2612,7 @@
     else if (PySlice_Check(item)) {
         Py_ssize_t start, stop, step, slicelength;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return -1;
         }
         slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 12be12b..6fcd995 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -584,7 +584,7 @@
     else if (PySlice_Check(key)) {
         Py_ssize_t start, stop, step, slicelength;
 
-        if (_PySlice_Unpack((PySliceObject *)key, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(key, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(get_shape0(view), &start, &stop,
@@ -663,7 +663,7 @@
     else if (PySlice_Check(key)) {
         Py_ssize_t stop, step;
 
-        if (_PySlice_Unpack((PySliceObject *)key, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(key, &start, &stop, &step) < 0) {
             return -1;
         }
         len = _PySlice_AdjustIndices(get_shape0(view), &start, &stop, step);
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index 3ac3811..8f17fca 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -286,7 +286,7 @@
 static PyObject*
 slice_indices(PySliceObject* self, PyObject* len)
 {
-    Py_ssize_t ilen, start, stop, step, slicelength;
+    Py_ssize_t ilen, start, stop, step;
 
     ilen = PyNumber_AsSsize_t(len, PyExc_OverflowError);
 
@@ -294,10 +294,10 @@
         return NULL;
     }
 
-    if (_PySlice_Unpack(self, &start, &stop, &step) < 0) {
+    if (_PySlice_Unpack((PyObject *)self, &start, &stop, &step) < 0) {
         return NULL;
     }
-    slicelength = _PySlice_AdjustIndices(ilen, &start, &stop, step);
+    _PySlice_AdjustIndices(ilen, &start, &stop, step);
 
     return Py_BuildValue("(nnn)", start, stop, step);
 }
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index ef4f8c1..c78e193 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1310,7 +1310,7 @@
         char* result_buf;
         PyObject* result;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(PyString_GET_SIZE(self), &start,
diff --git a/Objects/structseq.c b/Objects/structseq.c
index 9b3ba48..3e45840 100644
--- a/Objects/structseq.c
+++ b/Objects/structseq.c
@@ -114,7 +114,7 @@
         Py_ssize_t start, stop, step, slicelen, cur, i;
         PyObject *result;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelen = _PySlice_AdjustIndices(VISIBLE_SIZE(self), &start, &stop,
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 808156f..a61c8aa 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -715,7 +715,7 @@
         PyObject* it;
         PyObject **src, **dest;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(PyTuple_GET_SIZE(self), &start,
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 689529a..d011f7d 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -8008,7 +8008,7 @@
         Py_UNICODE* result_buf;
         PyObject* result;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(PyUnicode_GET_SIZE(self), &start,