Add tethering bootclasspath fragment to its sdk

This subsumes the java_sdk_library in the sdk.

Bug: 188427719
Test: build_mainline_modules.sh
Change-Id: Ib2ebb3893135b4dd91812f1f1b0915540cfd64cb
diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index f469d89..b5054cf 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -158,7 +158,5 @@
 
 sdk {
     name: "tethering-module-sdk",
-    java_sdk_libs: [
-        "framework-tethering",
-    ],
+    bootclasspath_fragments: ["com.android.tethering-bootclasspath-fragment"],
 }