bpo-42519: Replace PyObject_MALLOC() with PyObject_Malloc() (GH-23587)

No longer use deprecated aliases to functions:

* Replace PyObject_MALLOC() with PyObject_Malloc()
* Replace PyObject_REALLOC() with PyObject_Realloc()
* Replace PyObject_FREE() with PyObject_Free()
* Replace PyObject_Del() with PyObject_Free()
* Replace PyObject_DEL() with PyObject_Free()
diff --git a/Include/pymem.h b/Include/pymem.h
index 5b9dd42..92cd536 100644
--- a/Include/pymem.h
+++ b/Include/pymem.h
@@ -79,13 +79,15 @@ PyAPI_FUNC(void) PyMem_Free(void *ptr);
 
 
 // Deprecated aliases only kept for backward compatibility.
+// PyMem_Del and PyMem_DEL are defined with no parameter to be able to use
+// them as function pointers (ex: dealloc = PyMem_Del).
 #define PyMem_MALLOC(n)           PyMem_Malloc(n)
 #define PyMem_NEW(type, n)        PyMem_New(type, n)
 #define PyMem_REALLOC(p, n)       PyMem_Realloc(p, n)
 #define PyMem_RESIZE(p, type, n)  PyMem_Resize(p, type, n)
 #define PyMem_FREE(p)             PyMem_Free(p)
-#define PyMem_Del(p)              PyMem_Free(p)
-#define PyMem_DEL(p)              PyMem_Free(p)
+#define PyMem_Del                 PyMem_Free
+#define PyMem_DEL                 PyMem_Free
 
 
 #ifndef Py_LIMITED_API