Fix some more memory leaks + an invalid read.

`ProfMessage` was not completely initialized, fix this by using `calloc()`
for the allocation.

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/command/cmd_ac.c

@@ -1647,6 +1647,7 @@ cmd_ac_uninit(void)
     autocomplete_free(plugins_unload_ac);
     autocomplete_free(plugins_reload_ac);
     autocomplete_free(script_show_ac);
+    g_hash_table_destroy(ac_funcs);
 }
 
 static void