Fix compilation warnings

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/descrobject.c

@@ -67,11 +67,11 @@ int PyMethodDescr_Check(PyObject* method) {
     return UPCALL_CEXT_I(_jls_PyMethodDescr_Check, native_to_java(method));
 }
 
-typedef PyObject* (*PyDescr_NewClassMethod_fun_t)(void* name, 
+typedef PyObject* (*PyDescr_NewClassMethod_fun_t)(void* name,
                                                     const char* doc,
-                                                    int flags, 
-                                                    int wrapper, 
-                                                    void* methObj, 
+                                                    int flags,
+                                                    int wrapper,
+                                                    void* methObj,
                                                     void* primary);
 UPCALL_TYPED_ID(PyDescr_NewClassMethod, PyDescr_NewClassMethod_fun_t);
 PyObject* PyDescr_NewClassMethod(PyTypeObject *type, PyMethodDef *method) {
@@ -84,7 +84,7 @@ PyObject* PyDescr_NewClassMethod(PyTypeObject *type, PyMethodDef *method) {
                     type);
 }
 
-typedef PyObject* (*PyDescr_NewGetSet_fun_t)(void* name, 
+typedef PyObject* (*PyDescr_NewGetSet_fun_t)(void* name,
                                                     PyTypeObject *type,
                                                     void *get,
                                                     void *set,

graalpython/com.oracle.graal.python.cext/src/listobject.c

@@ -94,7 +94,7 @@ int PyList_SetSlice(PyObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v)
 
 UPCALL_ID(PyList_Extend);
 PyObject * _PyList_Extend(PyListObject *self, PyObject *iterable) {
-    return UPCALL_CEXT_O(_jls_PyList_Extend, native_to_java(self), native_to_java(iterable));
+    return UPCALL_CEXT_O(_jls_PyList_Extend, native_to_java((PyObject *)self), native_to_java(iterable));
 }
 
 UPCALL_ID(PyList_Sort);