tests/plugins: make howvec clean-up after itself.

TCG plugins are responsible for their own memory usage and although
the plugin_exit is tied to the end of execution in this case it is
still poor practice. Ensure we delete the hash table and related data
when we are done to be a good plugin citizen.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Message-Id: <20200225124710.14152-16-alex.bennee@linaro.org>

tests/plugin/howvec.c

@@ -163,6 +163,13 @@ static gint cmp_exec_count(gconstpointer a, gconstpointer b)
     return ea->count > eb->count ? -1 : 1;
 }
 
+static void free_record(gpointer data)
+{
+    InsnExecCount *rec = (InsnExecCount *) data;
+    g_free(rec->insn);
+    g_free(rec);
+}
+
 static void plugin_exit(qemu_plugin_id_t id, void *p)
 {
     g_autoptr(GString) report = g_string_new("Instruction Classes:\n");
@@ -195,30 +202,31 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
 
     counts = g_hash_table_get_values(insns);
     if (counts && g_list_next(counts)) {
-        GList *it;
-
         g_string_append_printf(report,"Individual Instructions:\n");
+        counts = g_list_sort(counts, cmp_exec_count);
 
-        it = g_list_sort(counts, cmp_exec_count);
-
-        for (i = 0; i < limit && it->next; i++, it = it->next) {
-            InsnExecCount *rec = (InsnExecCount *) it->data;
-            g_string_append_printf(report, "Instr: %-24s\t(%ld hits)\t(op=%#08x/%s)\n",
+        for (i = 0; i < limit && g_list_next(counts);
+             i++, counts = g_list_next(counts)) {
+            InsnExecCount *rec = (InsnExecCount *) counts->data;
+            g_string_append_printf(report,
+                                   "Instr: %-24s\t(%ld hits)\t(op=%#08x/%s)\n",
                                    rec->insn,
                                    rec->count,
                                    rec->opcode,
                                    rec->class ?
                                    rec->class->class : "un-categorised");
         }
-        g_list_free(it);
+        g_list_free(counts);
     }
 
+    g_hash_table_destroy(insns);
+
     qemu_plugin_outs(report->str);
 }
 
 static void plugin_init(void)
 {
-    insns = g_hash_table_new(NULL, g_direct_equal);
+    insns = g_hash_table_new_full(NULL, g_direct_equal, NULL, &free_record);
 }
 
 static void vcpu_insn_exec_before(unsigned int cpu_index, void *udata)