[not for review][lld-macho] Set allEntriesAreOmitted correctly for unwind info from ld -r

lld/MachO/UnwindInfoSection.cpp

void UnwindInfoSectionImpl<Ptr>::prepareRelocations(ConcatInputSection *isec) {
   // work. But since there are usually just few personality functions
   // that are referenced from many places, at least some of them likely
   // live, it wouldn't reduce number of got entries.
   for (size_t i = 0; i < isec->relocs.size(); ++i) {
     Reloc &r = isec->relocs[i];
     assert(target->hasAttr(r.type, RelocAttrBits::UNSIGNED));
 
     if (r.offset % sizeof(CompactUnwindEntry<Ptr>) == 0) {
-      if (auto *referentIsec = r.referent.dyn_cast<InputSection *>())
-        if (!cast<ConcatInputSection>(referentIsec)->shouldOmitFromOutput())
-          allEntriesAreOmitted = false;
+      InputSection *referentIsec;
+      if (auto *isec = r.referent.dyn_cast<InputSection *>())
+        referentIsec = isec;
+      else
+        referentIsec = cast<Defined>(r.referent.dyn_cast<Symbol *>())->isec;
+
       continue;
     }
 
     if (r.offset % sizeof(CompactUnwindEntry<Ptr>) !=
         offsetof(CompactUnwindEntry<Ptr>, personality))
       continue;
 
     if (auto *s = r.referent.dyn_cast<Symbol *>()) {