[NFC] Fix unused variable warning.

[dblaikie]

lld/COFF/Chunks.cpp

818–821

Rather than void casting the lambda, it's probably better to roll the lambda into the usage:

assert(std::unique(begin, begin + cnt, [](const RVAFlag &a, const RVAFlag &b) { return a.rva == b.rva; }) == begin + cnt && "...");

Also the lt lambda could be rolled into the std::sort call as well.

And perhaps making begin+cnt into an ArrayRef might be nice too. (then this code could use llvm::sort(container, comparator) for convenience - I don't think there's an llvm::unique that takes a container yet - but maybe someone will add one)

[dblaikie]

lld/COFF/Chunks.cpp

818–821

Ended up doing a few cleanups in e5b66a373414036db22d19647d913c2571df2701

lld/COFF/Chunks.cpp

void RVAFlagTableChunk::writeTo(uint8_t *buf) const {
   size_t cnt = 0;
   for (const ChunkAndOffset &co : syms) {
     begin[cnt].rva = co.inputChunk->getRVA() + co.offset;
     begin[cnt].flag = 0;
     ++cnt;
   }
   auto lt = [](RVAFlag &a, RVAFlag &b) { return a.rva < b.rva; };
   auto eq = [](RVAFlag &a, RVAFlag &b) { return a.rva == b.rva; };
+  (void)eq;
   std::sort(begin, begin + cnt, lt);
   assert(std::unique(begin, begin + cnt, eq) == begin + cnt &&
          "RVA tables should be de-duplicated");
 }
 
 // MinGW specific, for the "automatic import of variables from DLLs" feature.
 size_t PseudoRelocTableChunk::getSize() const {
   if (relocs.empty())
     return 0;
   return 12 + 12 * relocs.size();
 }