[lld] [lld-macho] Implement ObjC category merging (-objc_category_merging) (PR #82928)

[Kyungwoo Lee via llvm-commits]

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@@ -114,7 +120,12 @@ class ConcatInputSection final : public InputSection {
   bool isLive(uint64_t off) const override { return live; }
   void markLive(uint64_t off) override { live = true; }
   bool isCoalescedWeak() const { return wasCoalesced && symbols.empty(); }
-  bool shouldOmitFromOutput() const { return !live || isCoalescedWeak(); }
+  bool isLinkOptimizedAway() const override {
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kyulee-com wrote:

As discussed, I think we can simply update `live` instead of using this extra state and function.

https://github.com/llvm/llvm-project/pull/82928