Solve the problem that 'TYPE OCTECT STRING' fails to generate corresponding item.

ClassObj S1AP-PROTOCOL-IES ::= {
  { ID id-eNB-UE-S1AP-ID   CRITICALITY reject   TYPE ENB-UE-S1AP-ID  PRESENCE mandatory}|
  { ID id-S1-Message       CRITICALITY reject   TYPE OCTET STRING    PRESENCE mandatory}|
  ...
}

Set the key.sequence to eclass's _type_unique_index and increment
it in each object parsing call, then set the result back to
_type_unique_index field. It can keep a class-wise counter for
eash object instantiated.

This new method not only solve name duplication when union two
information object sets, but also avoid name duplication within
multiple instances of this class.

If one item's name already exists in this OPEN TYPE, simply do not
add it to expression open_type_choice.

It slightly modifies previous commit :
dcc822a0.

With this modification, asn1f_parameterization_fork() will fork
parameterization if rhs_pspecs and stored rhs_pspecs have different
constraints, e.g. expressions parameterized by different
VALUESET references. Associated information object tables will be
generated accordingly.

This file can be included and transformed via automake

The generated Makefile.am.example is not really in the automake style.
Renaming it to converter-example.mk to reflect that it is a plain makefile
snippet and that it is for creating the converter-example

Ref :

https://github.com/vlm/asn1c/pull/237#issuecomment-342356046