Bug#25800

  "Embedded server requires mysql.plugin"
  Embedded builds should not print any error when the mysql.plugin
  table does not exist. This is achieved by checking for the existance
  of the mysql.plugin table before attempting to open it and proceed
  silently if it does not exist.

sql/sql_plugin.cc

@@ -210,6 +210,11 @@ static void reap_plugins(void);
 /* declared in set_var.cc */
 extern sys_var *intern_find_sys_var(const char *str, uint length, bool no_error);
 
+#ifdef EMBEDDED_LIBRARY
+/* declared in sql_base.cc */
+extern bool check_if_table_exists(THD *thd, TABLE_LIST *table, bool *exists);
+#endif /* EMBEDDED_LIBRARY */
+
 
 /****************************************************************************
   Value type thunks, allows the C world to play in the C++ world
@@ -1299,6 +1304,9 @@ static void plugin_load(MEM_ROOT *tmp_root, int *argc, char **argv)
   READ_RECORD read_record_info;
   int error;
   THD *new_thd;
+#ifdef EMBEDDED_LIBRARY
+  bool table_exists;
+#endif /* EMBEDDED_LIBRARY */
   DBUG_ENTER("plugin_load");
 
   if (!(new_thd= new THD))
@@ -1315,6 +1323,20 @@ static void plugin_load(MEM_ROOT *tmp_root, int *argc, char **argv)
   tables.alias= tables.table_name= (char*)"plugin";
   tables.lock_type= TL_READ;
   tables.db= new_thd->db;
+
+#ifdef EMBEDDED_LIBRARY
+  /*
+    When building an embedded library, if the mysql.plugin table
+    does not exist, we silently ignore the missing table
+  */
+  pthread_mutex_lock(&LOCK_open);
+  if (check_if_table_exists(new_thd, &tables, &table_exists))
+    table_exists= FALSE;
+  pthread_mutex_unlock(&LOCK_open);
+  if (!table_exists)
+    goto end;
+#endif /* EMBEDDED_LIBRARY */
+
   if (simple_open_n_lock_tables(new_thd, &tables))
   {
     DBUG_PRINT("error",("Can't open plugin table"));