Add BuildCompat#isAtLeastNMR1() to API

Bug: 29332867
Change-Id: I1c5d2d5e384d722d2b6373498175a544535b66b2
diff --git a/v4/api/current.txt b/v4/api/current.txt
index bda93c5..76efae9 100644
--- a/v4/api/current.txt
+++ b/v4/api/current.txt
@@ -1865,6 +1865,7 @@
 
   public class BuildCompat {
     method public static boolean isAtLeastN();
+    method public static boolean isAtLeastNMR1();
   }
 
   public final class CancellationSignal {