Added missing system libraries and headers for bazel.

Change-Id: I966d28dd5a6677acc73c608a89efa30f8358b0dd
diff --git a/aos/linux_code/ipc_lib/BUILD b/aos/linux_code/ipc_lib/BUILD
index 83235ee..a8be135 100644
--- a/aos/linux_code/ipc_lib/BUILD
+++ b/aos/linux_code/ipc_lib/BUILD
@@ -55,6 +55,7 @@
     '//aos/linux_code/ipc_lib:mutex',
     ':core_lib',
     '//aos/common/logging:logging_interface',
+    '//external:librt',
   ],
 )