[lld] [ELF] Orphan placement: prefer the last similar section when its rank <= orphan's rank (PR #94099)

[Peter Smith via llvm-commits]

================
@@ -935,14 +935,18 @@ findOrphanPos(SmallVectorImpl<SectionCommand *>::iterator b,
       return i;
   }
 
-  // Find the first element that has as close a rank as possible.
   if (b == e)
     return e;
+  // Select the most similar output section. In case of ties, select the first
+  // section with a rank > the orphan's rank, or the last one with a rank <= the
+  // orphan's rank.
   int proximity = getRankProximity(sec, *b);
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smithp35 wrote:

The implementation getRankProximity needs to be understood before this part can be understood. Perhaps worth mentioning in the comment.
```
Rank Proximity is a value in the range [-1, 32] with -1 for SectionCommands with no input sections leaving [0, 32] to
describe the proximity with 0 most different and 32 identical.
``` 

Perhaps worth using `highestProximity` or `maxProximity` to make the purpose a bit clearer. Could even shorten to `maxP`. 

https://github.com/llvm/llvm-project/pull/94099