[lld] [LLD, MachO] Add `getUnwindInfoEncodingHash` to `BPSectionOrderer.cpp`. (PR #105587)

[Ellis Hoag via llvm-commits]

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@@ -60,6 +61,30 @@ getRelocHash(const Reloc &reloc,
   return getRelocHash(kind, sectionIdx.value_or(0), 0, reloc.addend);
 }
 
+// Get a hash of the unwind info (after relocation).
+// This hash is not 100% accurate, but it's good enough for compression.
+//
+// Unwind info will be eliminated if it is the same with its neighboors.
----------------
ellishg wrote:

```suggestion
// Unwind info will be eliminated if it is the same as its neighbors.
```

https://github.com/llvm/llvm-project/pull/105587