metrics_stdout: fix race detected by TSAN

srsenb/hdr/metrics_stdout.h

@@ -41,9 +41,9 @@ private:
   std::string int_to_hex_string(int value, int field_width);
   std::string float_to_eng_string(float f, int digits);
 
-  bool                   do_print;
-  uint8_t                n_reports;
-  enb_metrics_interface* enb;
+  std::atomic<bool>      do_print  = {false};
+  uint8_t                n_reports = 0;
+  enb_metrics_interface* enb       = nullptr;
 };
 
 } // namespace srsenb

srsue/hdr/metrics_stdout.h

@@ -50,7 +50,7 @@ private:
   std::string       float_to_eng_string(float f, int digits);
   void              print_table(const bool display_neighbours, const bool is_nr);
 
-  bool                  do_print             = false;
+  std::atomic<bool>     do_print             = {false};
   bool                  table_has_neighbours = false; ///< state of last table head
   uint8_t               n_reports            = 10;
   ue_metrics_interface* ue                   = nullptr;