Set system_lib_file for libs in tethering apex

The library (libcom.android.tethering.connectivity_native.so) in the
apex is a part of LLNDK. So it should be properly labelled so that
vendor can access it.

Bug: n/a
Test: m com.android.tethering
Test: adb shell -lZ /apex/com.android.tethering/lib64
Change-Id: I6c949c992042f4a38f25ca6f4243d31e81354467
diff --git a/apex/com.android.tethering-file_contexts b/apex/com.android.tethering-file_contexts
index 1b578ea..af366d8 100644
--- a/apex/com.android.tethering-file_contexts
+++ b/apex/com.android.tethering-file_contexts
@@ -1,2 +1,3 @@
 (/.*)?                  u:object_r:system_file:s0
 /bin/for-system/clatd   u:object_r:clatd_exec:s0
+/lib(64)?(/.*)          u:object_r:system_lib_file:s0