Fix BFLSC building.
diff --git a/miner.h b/miner.h
index ab753b6..94c6207 100644
--- a/miner.h
+++ b/miner.h
@@ -452,8 +452,10 @@ struct cgpu_info {
bool nonce_range;
bool polling;
bool flash_led;
+#endif /* USE_BITFORCE */
+#if defined(USE_BITFORCE) || defined(USE_BFLSC)
pthread_mutex_t device_mutex;
-#endif
+#endif /* USE_BITFORCE || USE_BFLSC */
enum dev_enable deven;
int accepted;
int rejected;