Proguard JNI methods

Keep JNI methods globally instead of just specific class ones.

(cribbed from //packages/modules/Connectivity/service/proguard.flags)

Test: TreeHugger
Bug: 387287282
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I2e8568855a7bad66233aa503ebd526c8826e0758

Tethering/proguard.flags

@@ -1,3 +1,6 @@
+# Keep JNI registered methods
+-keepclasseswithmembers,includedescriptorclasses class * { native <methods>; }
+
 # Keep class's integer static field for MessageUtils to parsing their name.
 -keepclassmembers class com.android.server.**,android.net.**,com.android.networkstack.** {
     static final % POLICY_*;
@@ -7,18 +10,6 @@
     static final % EVENT_*;
 }
 
--keep class com.android.networkstack.tethering.util.BpfMap {
-    native <methods>;
-}
-
--keep class com.android.networkstack.tethering.util.TcUtils {
-    native <methods>;
-}
-
--keep class com.android.networkstack.tethering.util.TetheringUtils {
-    native <methods>;
-}
-
 # Ensure runtime-visible field annotations are kept when using R8 full mode.
 -keepattributes RuntimeVisibleAnnotations,AnnotationDefault
 -keep interface com.android.networkstack.tethering.util.Struct$Field {