Used external roborio compiler instead of local compiler.

Change-Id: Ifec0d68b0b51a822c906bc4f52320004ee2f5d84
diff --git a/aos/linux_code/ipc_lib/BUILD b/aos/linux_code/ipc_lib/BUILD
index a8be135..077968b 100644
--- a/aos/linux_code/ipc_lib/BUILD
+++ b/aos/linux_code/ipc_lib/BUILD
@@ -55,7 +55,7 @@
     '//aos/linux_code/ipc_lib:mutex',
     ':core_lib',
     '//aos/common/logging:logging_interface',
-    '//external:librt',
+    '//debian:librt',
   ],
 )