Reminder to freeze keymaster at version "5"

Fixes: 155808722
Test: freeze-api produces error
Change-Id: I0b6d41a129f1a8cb064c394c73a3a70a6f2abc32
diff --git a/keymaster/aidl/Android.bp b/keymaster/aidl/Android.bp
index 3011da6..8d51e97 100644
--- a/keymaster/aidl/Android.bp
+++ b/keymaster/aidl/Android.bp
@@ -17,3 +17,12 @@
     },
     versions: ["1"],
 }
+
+// This is a reminder that the next version of keymaster should be frozen at
+// version "5" to avoid confusion with other versions of this interface.
+cc_library {
+    name: "android.hardware.keymaster-V3-java",
+}
+cc_library {
+    name: "android.hardware.keymaster-V4-java",
+}