Add a binder RPC for tethering stats.

Bug: 32163131
Bug: 64995262
Test: netd_{unit,integration}_test pass
Change-Id: I9c7dfdaf6b823840b1691761930b53c30a4dcbc3
diff --git a/server/NetdNativeService.h b/server/NetdNativeService.h
index d7503d5..87e3fc8 100644
--- a/server/NetdNativeService.h
+++ b/server/NetdNativeService.h
@@ -63,6 +63,7 @@
 
     // Tethering-related commands.
     binder::Status tetherApplyDnsInterfaces(bool *ret) override;
+    binder::Status tetherGetStats(android::os::PersistableBundle *ret) override;
 
     binder::Status interfaceAddAddress(const std::string &ifName,
             const std::string &addrString, int prefixLength) override;