[src] Fix incorrect invocation of mutex in nnet-batch-compute code (#2932)

src/nnet3/nnet-batch-compute.cc

@@ -135,7 +135,7 @@ NnetBatchComputer::GetHighestPriorityComputation(
     int32 *minibatch_size_out,
     std::vector<NnetInferenceTask*> *tasks) {
   tasks->clear();
-  std::unique_lock<std::mutex>(mutex_);
+  std::unique_lock<std::mutex> lock(mutex_);
   MapType::iterator iter = tasks_.begin(), end = tasks_.end(),
       best_iter = tasks_.end();
   double highest_priority = -std::numeric_limits<double>::infinity();

src/nnet3/nnet-compute.h

@@ -119,7 +119,7 @@ class NnetComputer {
 
   // Version of GetOutput that calls Swap(), destroying the output stored inside
   // this object.  You should probably not use this if you plan to call
-  // Backward() on the same NnetComputer object, or it's a recurret
+  // Backward() on the same NnetComputer object, or it's a recurrent
   // computation-- it may lead to a crash.
   void GetOutputDestructive(const std::string &output_name,
                             CuMatrix<BaseFloat> *output);