Suppress NewApi warnings for @SystemApi -> public APIs

Android Lint doesn't handle API change from @SystemApi to public API
correctly (see b/193460475). We have to manually suppress those
warnings for now.

This CL suppresses warnings related to:
 - IpPrefix(InetAddress, int)
 - RouteInfo#getType

Bug: 186082280
Test: presubmit
Change-Id: Ib24b2d3fb21b86bd9e3555316a5a5bcb94434c00
diff --git a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
index e78e336..de13d42 100644
--- a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
+++ b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
@@ -23,6 +23,7 @@
 import static android.net.RouteInfo.RTN_UNREACHABLE;
 import static android.system.OsConstants.EBUSY;
 
+import android.annotation.SuppressLint;
 import android.net.INetd;
 import android.net.InterfaceConfigurationParcel;
 import android.net.IpPrefix;
@@ -213,6 +214,7 @@
         return failures;
     }
 
+    @SuppressLint("NewApi")
     private static String findNextHop(final RouteInfo route) {
         final String nextHop;
         switch (route.getType()) {