include/config-win.h:
  Undefine ERROR #defined by WINGDI
sql/sql_class.cc:
  Fix to compile with msvc: converted static const int Item_arena::* to enum members
sql/sql_class.h:
  Fix to compile with msvc: converted static const int Item_arena::* to enum members
sql/sql_prepare.cc:
  Fix to compile with msvc: converted static const int Item_arena::* to enum members