[onert] Apply inline variable to Exectime

This commit applies inline variable to class Exectime.

ONE-DCO-1.0-Signed-off-by: ragmani <[email protected]>

runtime/onert/core/src/exec/ExecTime.h

@@ -93,13 +93,13 @@ class ExecTime
    * @brief Update metrics file with new data.
    */
   void storeOperationsExecTime() const { _json.storeOperationsExecTime(); }
-  static const int64_t NOT_FOUND = -1;
+  inline static const int64_t NOT_FOUND = -1;
 
 private:
   /// @brief Measurement data, which is shared with serializer
   MeasurementData _measurements;
   // int64_t::max may cause integer overflow
-  static const int64_t _MAX = std::numeric_limits<int32_t>::max();
+  inline static const int64_t _MAX = std::numeric_limits<int32_t>::max();
   /// @brief Serializer
   JSON _json;
 };