Keep primitive members used by MessageUtils.

This includes in particular {Full,Network}Score.POLICY_* members
which were removed recently.

Before :
  Policies : 55&62&63
After :
  Policies : EVER_EVALUATED&EVER_VALIDATED&IS_VALIDATED

This patch also unifies the directives under Tethering/ for
simplicity.

Test: adb logcat & dumpsys connectivity & dumpsys tethering
Change-Id: I3d231fbaaebe233b2633da8bb880b5ad1613a32f
diff --git a/Tethering/proguard.flags b/Tethering/proguard.flags
index 2905e28..109bbda 100644
--- a/Tethering/proguard.flags
+++ b/Tethering/proguard.flags
@@ -1,7 +1,10 @@
 # Keep class's integer static field for MessageUtils to parsing their name.
--keep class com.android.networkstack.tethering.Tethering$TetherMainSM {
-    static final int CMD_*;
-    static final int EVENT_*;
+-keepclassmembers class com.android.server.**,android.net.**,com.android.networkstack.** {
+    static final % POLICY_*;
+    static final % NOTIFY_TYPE_*;
+    static final % TRANSPORT_*;
+    static final % CMD_*;
+    static final % EVENT_*;
 }
 
 -keep class com.android.networkstack.tethering.util.BpfMap {
@@ -21,12 +24,8 @@
     *;
 }
 
--keepclassmembers class android.net.ip.IpServer {
-    static final int CMD_*;
-}
-
 # The lite proto runtime uses reflection to access fields based on the names in
 # the schema, keep all the fields.
 -keepclassmembers class * extends com.android.networkstack.tethering.protobuf.MessageLite {
     <fields>;
-}
\ No newline at end of file
+}