Change in flashrom[master]: layout: Use linked list for `struct romentry`

[Peter Marheine (Code Review)]

Attention is currently required from: Nico Huber, Edward O'Callaghan, Daniel Campello, Anastasia Klimchuk.
Peter Marheine has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/33521 )

Change subject: layout: Use linked list for `struct romentry`
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Patch Set 4:

(2 comments)

File layout.c:

https://review.coreboot.org/c/flashrom/+/33521/comment/56c4b7ae_0fab7a11 
PS4, Line 369: 	return iterator ? iterator->next : layout->head;
This duplicates _layout_next. Should one of them be removed?

https://review.coreboot.org/c/flashrom/+/33521/comment/f2d8a31d_c000959d 
PS4, Line 418: 	entry->next	= layout->head;
Shouldn't this be NULL? Otherwise it's creating a reference cycle.