+/* Given a WIM that from which one or all of the images is being written, build
+ * the list of unique streams ('struct wim_lookup_table_entry's) that must be
+ * written, plus any unhashed streams that need to be written but may be
+ * identical to other hashed or unhashed streams being written. These unhashed
+ * streams are checksummed while the streams are being written. To aid this
+ * process, the member @unique_size is set to 1 on streams that have a unique
+ * size and therefore must be written.
+ *
+ * The out_refcnt member of each 'struct wim_lookup_table_entry' is set to
+ * indicate the number of times the stream is referenced in only the streams
+ * that are being written; this may still be adjusted later when unhashed
+ * streams are being resolved.
+ */