[llvm] [nfc][InstrFDO]Encapsulate header writes in a class member function (PR #90142)

[Kazu Hirata via llvm-commits]

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@@ -788,12 +805,12 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
     // Now do the final patch:
     PatchItem PatchItems[] = {
         // Patch the Header.HashOffset field.
-        {HashTableStartFieldOffset, &HashTableStart, 1},
+        {BackPatchStartOffset, &HashTableStart, 1},
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kazutakahirata wrote:

Likewise, I suggest grouping these fields.

https://github.com/llvm/llvm-project/pull/90142