A cleanup for MDEV-13415 Wrap the code in sp.cc into a class Sp_handler

Fixing mysql_execute_command() and store_schema_proc() not to use
stored object type codes TYPE_ENUM_PROCEDURE and TYPE_ENUM_FUNCTION.
Using pointers to Sp_handler instead, to make the code symmetric across
existing (function,procedure) and future (e.g package) SP object types.

sql/sql_parse.cc

@@ -5405,11 +5405,10 @@ mysql_execute_command(THD *thd)
     }
     if (first_table)
     {
-      if (lex->type == TYPE_ENUM_PROCEDURE ||
-          lex->type == TYPE_ENUM_FUNCTION)
+      const Sp_handler *sph= Sp_handler::handler((stored_procedure_type)
+                                                 lex->type);
+      if (sph)
       {
-        const Sp_handler *sph= Sp_handler::handler((stored_procedure_type)
-                                                   lex->type);
         uint grants= lex->all_privileges 
 		   ? (PROC_ACLS & ~GRANT_ACL) | (lex->grant & GRANT_ACL)
 		   : lex->grant;

sql/sql_show.cc

@@ -6031,10 +6031,7 @@ bool store_schema_proc(THD *thd, TABLE *table, TABLE *proc_table,
       check_some_routine_access(thd, db.str, name.str, sph))
     return 0;
 
-  if ((lex->sql_command == SQLCOM_SHOW_STATUS_PROC &&
-      sph->type() == TYPE_ENUM_PROCEDURE) ||
-      (lex->sql_command == SQLCOM_SHOW_STATUS_FUNC &&
-      sph->type() == TYPE_ENUM_FUNCTION) ||
+  if (sph == Sp_handler::handler(lex->sql_command)||
       (sql_command_flags[lex->sql_command] & CF_STATUS_COMMAND) == 0)
   {
     restore_record(table, s->default_values);