util: use alloca0() intead of alloca() + memzero()

src/python-systemd/_journal.c

@@ -41,8 +41,7 @@ static PyObject *journal_sendv(PyObject *self, PyObject *args) {
 
         /* Allocate an array for the argument strings */
         argc = PyTuple_Size(args);
-        encoded = alloca(argc * sizeof(PyObject*));
-        memzero(encoded, argc * sizeof(PyObject*));
+        encoded = alloca0(argc * sizeof(PyObject*));
 
         /* Allocate sufficient iovector space for the arguments. */
         iov = alloca(argc * sizeof(struct iovec));

src/readahead/readahead-collect.c

@@ -129,8 +129,7 @@ static int pack_file(FILE *pack, const char *fn, bool on_btrfs) {
         }
 
         pages = l / page_size();
-        vec = alloca(pages);
-        memzero(vec, pages);
+        vec = alloca0(pages);
         if (mincore(start, l, vec) < 0) {
                 log_warning("mincore(%s) failed: %m", fn);
                 r = -errno;