[BOLT] Fix data race in shortenInstructions

Address ThreadSanitizer warning

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D121338

bolt/lib/Passes/BinaryPasses.cpp

@@ -1015,6 +1015,7 @@ uint64_t ShortenInstructions::shortenInstructions(BinaryFunction &Function) {
         continue;
 
       if (opts::Verbosity > 2) {
+        BC.scopeLock();
         outs() << "BOLT-INFO: shortening:\nBOLT-INFO:    ";
         BC.printInstruction(outs(), OriginalInst, 0, &Function);
         outs() << "BOLT-INFO: to:";