Build fix due to prograud changes

Change-Id: I161020ecb2a1786fc9184d024208cac4efc4052f
diff --git a/proguard.flags b/proguard.flags
index 51abcca..a315cdc 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -86,13 +86,15 @@
   public <init>(...);
 }
 
+# The support library contains references to newer platform versions.
+# Don't warn about those in case this app is linking against an older
+# platform version.  We know about them, and they are safe.
+-dontwarn android.support.**
+
 # Proguard will strip methods required for talkback to properly scroll to
 # next row when focus is on the last item of last row when using a RecyclerView
 # Keep optimized and shrunk proguard to prevent issues like this when using
 # support jar.
-#-keep,allowoptimization,allowshrinking class android.support.** {
-#  *;
-#}
 -keep class android.support.v7.widget.RecyclerView { *; }
 
 -keep interface com.android.launcher3.userevent.nano.LauncherLogProto.** {