ghidra: df_import_structures does not appear to handle base-type on enum instances

[ab9rf]

For example, intrigue_corruption::offered_relationship is an enum of type vague_relationship_type with an overridden base type of int32_t but the type is imported into ghidra as 2 bytes long, matching the underlying type of the enum but ignoring the override.

the specific xml for this example is:
<enum name='offered_relationship' type-name='vague_relationship_type' base-type='int32_t'/>

this should result in a 4-byte allocation for that field, but in the structure actually generated by df_import_structures the allocation is 2 bytes. in this particular instance, padding insertion prevents an issue, but this is happenstance