Change LLVM bitcode linking to use tree reduction to scale better

llvm/tools/llc/llc.cpp

Index: llvm/tools/llc/llc.cpp
===================================================================
--- a/llvm/tools/llc/llc.cpp
+++ b/llvm/tools/llc/llc.cpp
@@ -710,10 +710,10 @@
   // we have a NeededRecord for one of them.
   // They may have been eliminated by the StripDeadPrototypes pass,
   // or some other pass that is unaware of NeededRecords / IntrinsicLowering.
-  IntrinsicLowering IL(*target->getTargetData());
-  IL.AddPrototypes(*M);
+  if (!MetadataTextFilename.empty()) {
+    IntrinsicLowering IL(*target->getTargetData());
+    IL.AddPrototypes(*M);
 
-  if (!MetadataTextFilename.empty()) {
     int err = WriteTextMetadataFile(*M.get(), TheTriple);
     if (err != 0)
       return err;