This commit does 3 changes:
1. Introduce new option `oo_inherits_not_specialized` indicating if
somewhere in the inheritance chain of an object there is a non
specialized generic parameter
2. Avoid building the VMT for an object which has a generic parameter in
the inheritance chain (fixes#40983)
3. When no vmt is build `insert_struct_hidden_paras` usually called as
part of `build_vmt` will be called seperately to add missing
parameters
