Add a hacky workaround when freopen hangs in a deadlock

lib/Sandbox/ProcessSandbox.cpp

@@ -101,11 +101,16 @@ mull::ExecutionResult mull::ForkTimerSandbox::run(Diagnostics &diagnostics,
   auto start = high_resolution_clock::now();
   const pid_t workerPID = mullFork(diagnostics, "worker");
   if (workerPID == 0) {
+    /// TODO: There is an issue with freopen: it hangs once in a while, so as a hack we add the
+    /// timeout handling before calling freopen. There is a bug somewhere and it needs to be fixed.
+    /// It happens only on macOS, here is the most relevant thread:
+    /// hangs in flockfile() during fread() or fclose()
+    /// https://groups.google.com/forum/#!topic/darwin-dev/e5qPebpfvYM
+    handle_timeout(timeoutMilliseconds);
+
     freopen(stderrFilename.c_str(), "w", stderr);
     freopen(stdoutFilename.c_str(), "w", stdout);
 
-    handle_timeout(timeoutMilliseconds);
-
     *sharedStatus = function();
 
     fflush(stderr);