[BOLT][NFCI] Remove redundant code

[maksfb]

Summary

createBasicBlock() will create a label for addBasicBlock().

bolt/include/bolt/Core/BinaryFunction.h

public:
   /// on the alignment of the existing offset.
   ///
   /// Returns NULL if basic block already exists at the \p Offset.
   BinaryBasicBlock *addBasicBlock(uint64_t Offset, MCSymbol *Label = nullptr,
                                   bool DeriveAlignment = false) {
     assert((CurrentState == State::CFG || !getBasicBlockAtOffset(Offset)) &&
            "basic block already exists in pre-CFG state");
 
-    if (!Label) {
-      std::unique_lock<std::shared_timed_mutex> Lock(BC.CtxMutex);
-      Label = BC.Ctx->createNamedTempSymbol("BB");
-    }
     std::unique_ptr<BinaryBasicBlock> BBPtr =
         createBasicBlock(Offset, Label, DeriveAlignment);
     BasicBlocks.emplace_back(BBPtr.release());
 
     BinaryBasicBlock *BB = BasicBlocks.back();
     BB->setIndex(BasicBlocks.size() - 1);
 
     if (CurrentState == State::Disassembled) {