Undefine MAX_NODE and rename some variables

Undefine MAX_NODE when it is not used. Also, rename MAX_NODE to
MAX_NODES and not_stable to unstable.

Rename node_ptr to nodes

qtest.c

@@ -602,16 +602,16 @@ bool do_sort(int argc, char *argv[])
     set_noallocate_mode(true);
 
 /* If the number of elements is too large, it may take a long time to check the
- * stability of the sort. So, MAX_NODE is used to limit the number of elements
+ * stability of the sort. So, MAX_NODES is used to limit the number of elements
  * to check the stability of the sort. */
-#define MAX_NODE 100000
-    struct list_head *node_ptrs[MAX_NODE];
+#define MAX_NODES 1000000
+    struct list_head *nodes[MAX_NODES];
     unsigned no = 0;
     if (current && current->size) {
         element_t *entry;
         list_for_each_entry (entry, current->q, list) {
-            node_ptrs[no++] = &entry->list;
-            if (no >= MAX_NODE) {
+            nodes[no++] = &entry->list;
+            if (no >= MAX_NODES) {
                 report(1,
                        "Skip the stability check because the number of "
                        "elements is too large.");
@@ -645,18 +645,18 @@ bool do_sort(int argc, char *argv[])
                 break;
             }
             /* Ensure the stability of the sort */
-            if (no < MAX_NODE && !strcmp(item->value, next_item->value)) {
-                bool not_stable = false;
-                for (unsigned i = 0; i < MAX_NODE; i++) {
-                    if (node_ptrs[i] == cur_l->next) {
-                        not_stable = true;
+            if (no < MAX_NODES && !strcmp(item->value, next_item->value)) {
+                bool unstable = false;
+                for (unsigned i = 0; i < MAX_NODES; i++) {
+                    if (nodes[i] == cur_l->next) {
+                        unstable = true;
                         break;
                     }
-                    if (node_ptrs[i] == cur_l) {
+                    if (nodes[i] == cur_l) {
                         break;
                     }
                 }
-                if (not_stable) {
+                if (unstable) {
                     report(
                         1,
                         "ERROR: Not stable sort. The duplicate strings \"%s\" "
@@ -668,6 +668,7 @@ bool do_sort(int argc, char *argv[])
             }
         }
     }
+#undef MAX_NODE
 
     q_show(3);
     return ok && !error_check();