[clangd] Disable new errs()-tie behavior, it's racy.

clang-tools-extra/clangd/tool/ClangdMain.cpp

)";
   // If a user ran `clangd` in a terminal without redirecting anything,
   // it's somewhat likely they're confused about how to use clangd.
   // Show them the help overview, which explains.
   if (llvm::outs().is_displayed() && llvm::errs().is_displayed())
     llvm::errs() << Overview << "\n";
   // Use buffered stream to stderr (we still flush each log message). Unbuffered
   // stream can cause significant (non-deterministic) latency for the logger.
   llvm::errs().SetBuffered();
+  // Don't flush stdout when logging, this would be both slow and racy!
+  llvm::errs().tie(nullptr);
   StreamLogger Logger(llvm::errs(), LogLevel);
   LoggingSession LoggingSession(Logger);
   // Write some initial logs before we start doing any real work.
   log("{0}", clang::getClangToolFullVersion("clangd"));
   log("PID: {0}", llvm::sys::Process::getProcessId());
   {
     SmallString<128> CWD;
     if (auto Err = llvm::sys::fs::current_path(CWD))