[llvm] [BOLT][DWARF] Refactor legacy ranges writers (PR #96006)

[Maksim Panchenko via llvm-commits]

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@@ -1605,6 +1613,32 @@ void DWARFRewriter::finalizeCompileUnits(DIEBuilder &DIEBlder,
                                          DIEStreamer &Streamer,
                                          CUOffsetMap &CUMap,
                                          const std::list<DWARFUnit *> &CUs) {
+  for (DWARFUnit *CU : CUs) {
+    if (CU->getVersion() != 4)
+      continue;
+    if (std::optional<uint64_t> DWOId = CU->getDWOId()) {
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maksfb wrote:

nit: use early `continue` here as well to reduce indentation.

https://github.com/llvm/llvm-project/pull/96006