Missing export symbol for type_handler_enum and type_handler_set

The symbol of type_handler_enum and type_handler_set are not export.
So, these variables can't use in the storage engine as below.

(ha_mroonga is Mronnga's code. Mroonga( https://mroonga.org/ ) is a MySQL storage engine based on Groonga, the full text search engine.)

ha_mroonga.obj : error LNK2001: unresolved external symbol "class Named_type_handler<class Type_handler_enum> type_handler_enum" (?type_handler_enum@@3V?$Named_type_handler@VType_handler_enum@@@@A) [C:\projects\build\storage\mroonga\mroonga.vcxproj]
ha_mroonga.obj : error LNK2001: unresolved external symbol "class Named_type_handler<class Type_handler_set> type_handler_set" (?type_handler_set@@3V?$Named_type_handler@VType_handler_set@@@@A) [C:\projects\build\storage\mroonga\mroonga.vcxproj]

This error occurs since mariadb-server-10.5.5.

I think that we need to export these symbols as below.

--- mariadb-10.5.5.orig/sql/sql_type.h	2020-09-09 13:20:40.113007137 +0900

+++ mariadb-10.5.5/sql/sql_type.h	2020-09-09 13:23:17.385795235 +0900

@@ -7298,8 +7298,8 @@ extern MYSQL_PLUGIN_IMPORT Named_type_ha

 extern Named_type_handler<Type_handler_bit>         type_handler_bit;

-extern Named_type_handler<Type_handler_enum>        type_handler_enum;

-extern Named_type_handler<Type_handler_set>         type_handler_set;

+extern MYSQL_PLUGIN_IMPORT Named_type_handler<Type_handler_enum>        type_handler_enum;

+extern MYSQL_PLUGIN_IMPORT Named_type_handler<Type_handler_set>         type_handler_set;

 extern Named_type_handler<Type_handler_string>      type_handler_string;

 extern Named_type_handler<Type_handler_var_string>  type_handler_var_string;