Adding version code R for development

Test: Builds

Bug: 129975435
Change-Id: I26ef76266b2f52746ca08a45f5013c580cecd4fb
Merged-In: I26ef76266b2f52746ca08a45f5013c580cecd4fb
(cherry picked from commit 1d081c503c)

api/current.txt

@@ -34211,6 +34211,7 @@ package android.os {
     field public static final int O_MR1 = 27; // 0x1b
     field public static final int P = 28; // 0x1c
     field public static final int Q = 29; // 0x1d
+    field public static final int R = 10000; // 0x2710
   }
 
   public final class Bundle extends android.os.BaseBundle implements java.lang.Cloneable android.os.Parcelable {

core/java/android/os/Build.java

@@ -992,6 +992,11 @@ public class Build {
          * engaged. It's now time to see if you can dance.</em>
          */
         public static final int Q = 29;
+
+        /**
+         * R.
+         */
+        public static final int R = CUR_DEVELOPMENT;
     }
 
     /** The type of build, like "user" or "eng". */