Fixed linker issue

dump1090.c

@@ -51,6 +51,8 @@
 
 #include <stdarg.h>
 
+struct modeStruct Modes;
+
 //
 // ============================= Utility functions ==========================
 //

dump1090.h

@@ -294,7 +294,7 @@ struct mag_buf {
 };
 
 // Program global state
-struct {                             // Internal state
+struct modeStruct {                             // Internal state
     pthread_t       reader_thread;
 
     pthread_mutex_t data_mutex;      // Mutex to synchronize buffer access
@@ -392,7 +392,9 @@ struct {                             // Internal state
     int stats_latest_1min;
     struct stats stats_5min;
     struct stats stats_15min;
-} Modes;
+};
+
+extern struct modeStruct Modes;
 
 // The struct we use to store information about a decoded message.
 struct modesMessage {