backtrace support api

include/spdlog/sinks/dist_sink.h

@@ -45,6 +45,12 @@ public:
         sinks_ = std::move(sinks);
     }
 
+    std::vector<std::shared_ptr<sink>>& sinks()
+    {
+        return sinks_;
+    }
+
+
 protected:
     void sink_it_(const details::log_msg &msg) override
     {