add USER_UNSAFE_USE

lib_xua/src/core/main.xc

@@ -405,6 +405,9 @@ void usb_audio_io(chanend ?c_aud_in,
 #define USER_MAIN_CORES
 #endif
 
+#ifndef USER_UNSAFE_USE
+#define USER_UNSAFE_USE
+#endif
 
 /* Main for USB Audio Applications */
 int main()
@@ -582,6 +585,9 @@ int main()
         on tile[AUDIO_IO_TILE]:
         {
             /* Audio I/O task, includes mixing etc */
+            //user unsafe use
+            USER_UNSAFE_USE
+
             usb_audio_io(c_mix_out
 #if (XUA_SPDIF_TX_EN) && (SPDIF_TX_TILE != AUDIO_IO_TILE)
                 , c_spdif_tx