logger: check if we are in replay mode via ENV variable 'replay'

src/modules/logger/logger.h

@@ -85,7 +85,7 @@ public:
 	 * before starting the logger.
 	 * @param file_name file name of the used log replay file. Will be copied.
 	 */
-	static void setReplayFile(const char *file_name);
+	void setReplayFile(const char *file_name);
 
 	/**
 	 * Add a topic to be logged. This must be called before start_log()
@@ -233,8 +233,7 @@ private:
 	param_t						_log_utc_offset;
 	orb_advert_t					_mavlink_log_pub = nullptr;
 	uint16_t					_next_topic_id; ///< id of next subscribed topic
-
-	static char		*_replay_file_name;
+	char						*_replay_file_name = nullptr;
 };
 
 } //namespace logger