fix Issue 12146 - Linker error with __xopCmp, __xopEq, TypeInfo

- The root cause for this bug was, that the TypeInfo
  for structs can only be generated after semantic3 for
  that struct was run. This is not possible if the TypeInfo
  is needed during the obj generation pass, e.g. because
  it is referenced by an array TypeInfo.

- Fixed by eagerly emitting TypeInfo for structs,
  this is similar to TypeInfos for classes.