Fix proguard flags.

Fixes a crash in the new hotseat launcher icons.

Change-Id: Idcb7441647f16c783a47dfe09400f04fa8980dd3
diff --git a/proguard.flags b/proguard.flags
index 255f970..1187fd8 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -1,6 +1,7 @@
 -keep class com.android.launcher2.Launcher {
   public void previousScreen(android.view.View);
   public void nextScreen(android.view.View);
+  public void launchHotSeat(android.view.View);
 }
 
 -keep class com.android.launcher2.AllApps3D$Defines {