The aforementioned error message displayed during processing the following ASN.1 excerpt.

S1AP-ELEMENTARY-PROCEDURES S1AP-ELEMENTARY-PROCEDURE ::= {
    S1AP-ELEMENTARY-PROCEDURES-CLASS-1 |
    S1AP-ELEMENTARY-PROCEDURES-CLASS-2,
    ...
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-1 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverPreparation                |
...
    writeReplaceWarning,
    ...,
    uERadioCapabilityMatch             |
....
    uEContextResume
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-2 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverNotification               |
...
    privateMessage,
    ...,
    downlinkUEAssociatedLPPaTransport  |
...
    mMECPRelocationIndication
}

Because S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and S1AP-ELEMENTARY-PROCEDURES-CLASS-2
are resolved 'after' S1AP-ELEMENTARY-PROCEDURES, so the ioc tables of them are not
available during resolving S1AP-ELEMENTARY-PROCEDURES. So we can not drop the
latter's containedSubtype field at first pass of asn1f_resolve_constraints of fix
process.

We also add second pass of asn1f_resolve_constraints to have a chance to combine
ioc tables of S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and
S1AP-ELEMENTARY-PROCEDURES-CLASS-2.