Semms to make a difference.

Author: johnno1962

lld/MachO/Driver.cpp

@@ -297,8 +297,8 @@ using DeferredFiles = std::vector<DeferredFile>;
 // the process is not stalled waiting on disk buffer i/o.
 void multiThreadedPageInBackground(const DeferredFiles &deferred) {
   static size_t pageSize = Process::getPageSizeEstimate(), totalBytes;
+  static std::mutex mutex;
   size_t index = 0;
-  std::mutex mutex;
 
   parallelFor(0, config->readThreads, [&](size_t I) {
     while (true) {