CBMC does not ignore the is_padding comment on datatype fields

[danielsn]

On a datatype_parameter, the field is marked with the following named sub if its padding

                    "#is_padding": {
                      "id": "1"
                    },

CBMC appears to consider two structs to have different types if they agree on all fields, but disagree on which ones have the #is_padding comments. Aren't comments supposed to be ignored when comparing equality?

[tautschnig]

On a second look, this doesn't seem to be #is_padding that's causing trouble. It's #5815, again, as a padding member looks like this:

    2:
      * type: unsignedbv
          * width: 24
      * #is_padding: 1
      * name: $pad2

Note the absence of pretty_name, which the C front-end otherwise does always seem to set.

[jimgrundy]

Dropping AWS label after review with @danielsn as there is no particular AWS interest.