Make CONNECTIVITY_USE_RESTRICTED_NETWORKS @SystemApi.

Fix: 34721574
Test: builds, apicheck passes
Change-Id: If921f265c02ffb57d5ac717f924f91f664dd991f
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 7d4f99d..c3b2aa1 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1300,7 +1300,7 @@
     <permission android:name="android.permission.CONNECTIVITY_INTERNAL"
         android:protectionLevel="signature|privileged" />
 
-    <!-- Allows an internal user to use restricted Networks.
+    <!-- @SystemApi Allows an internal user to use restricted Networks.
          @hide -->
     <permission android:name="android.permission.CONNECTIVITY_USE_RESTRICTED_NETWORKS"
         android:protectionLevel="signature|privileged" />