[NS08] Expose public NetworkScore API

This exposes the two bits settable by the network agents in
Android S on NetworkScore. This is meant to be extensible in
future releases, or possibly for OEM upstreams.

Test: builds
CTS-Coverage-Bug: 184037351
Bug: 167544279
Merged-In: I3c2563d4ae4e3715d0c6270344ba8f7ef067872f
Merged-In: Id7ee1bd3e2679f0bd5200d5c299f18a33b87847c
Change-Id: Id7ee1bd3e2679f0bd5200d5c299f18a33b87847c
  (cherry-picked from ag/14010221)
diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index ab0f8f2..27836c1 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -343,6 +343,8 @@
     method public int describeContents();
     method public int getKeepConnectedReason();
     method public int getLegacyInt();
+    method public boolean isExiting();
+    method public boolean isTransportPrimary();
     method public void writeToParcel(@NonNull android.os.Parcel, int);
     field @NonNull public static final android.os.Parcelable.Creator<android.net.NetworkScore> CREATOR;
     field public static final int KEEP_CONNECTED_FOR_HANDOVER = 1; // 0x1
@@ -352,8 +354,10 @@
   public static final class NetworkScore.Builder {
     ctor public NetworkScore.Builder();
     method @NonNull public android.net.NetworkScore build();
+    method @NonNull public android.net.NetworkScore.Builder setExiting(boolean);
     method @NonNull public android.net.NetworkScore.Builder setKeepConnectedReason(int);
     method @NonNull public android.net.NetworkScore.Builder setLegacyInt(int);
+    method @NonNull public android.net.NetworkScore.Builder setTransportPrimary(boolean);
   }
 
   public final class OemNetworkPreferences implements android.os.Parcelable {