Fix deadlock issue with mingw in async logger

include/spdlog/details/mpmc_blocking_q.h

@@ -33,36 +33,30 @@ public:
     // try to enqueue and block if no room left
     void enqueue(T &&item)
     {        
-        {
-            std::unique_lock<std::mutex> lock(queue_mutex_);
-            pop_cv_.wait(lock, [this] { return !this->q_.full(); });
-            q_.push_back(std::move(item));
-        }
-        push_cv_.notify_one();
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        pop_cv_.wait(lock, [this] { return !this->q_.full(); });
+        q_.push_back(std::move(item));        
+		push_cv_.notify_one();
     }
 
     // enqueue immediately. overrun oldest message in the queue if no room left.
     void enqueue_nowait(T &&item)
     {        
-        {
-            std::unique_lock<std::mutex> lock(queue_mutex_);
-            q_.push_back(std::move(item));
-        }
-        push_cv_.notify_one();
+        std::unique_lock<std::mutex> lock(queue_mutex_);
+        q_.push_back(std::move(item));       
+		push_cv_.notify_one();
     }
 
     // try to dequeue item. if no item found. wait upto timeout and try again
     // Return true, if succeeded dequeue item, false otherwise
     bool dequeue_for(T &popped_item, std::chrono::milliseconds wait_duration)
     {        
-        {
-            std::unique_lock<std::mutex> lock(queue_mutex_);
-            if (!push_cv_.wait_for(lock, wait_duration, [this] { return !this->q_.empty(); }))
-            {
-                return false;
-            }
-            q_.pop_front(popped_item);
-        }
+		std::unique_lock<std::mutex> lock(queue_mutex_);
+		if (!push_cv_.wait_for(lock, wait_duration, [this] { return !this->q_.empty(); }))
+		{
+			return false;
+		}
+		q_.pop_front(popped_item);        
         pop_cv_.notify_one();
         return true;
     }