handle a ECPG_bytea typo

Hi, hackers

The source looks like:

    case ECPGt_bytea:
    {
        struct ECPGgeneric_varchar *variable =
        (struct ECPGgeneric_varchar *) (var->value);

        ......
    }

I think the developer intend to use struct ECPGgeneric_bytea instead of struct ECPGgeneric_varchar

Is this thoughts right?

I have wrote a patch to fix this typo