Add boot animation progress system property.

Test: m
Bug: 175686819
Change-Id: Ic2757054b908e2c7ff51e256e8683616df74fb33
diff --git a/rootdir/init.rc b/rootdir/init.rc
index d033afc..a233fbe 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -1072,6 +1072,7 @@
     class_start main
     class_start late_start
     setprop service.bootanim.exit 0
+    setprop service.bootanim.progress 0
     start bootanim
 
 on property:vold.decrypt=trigger_shutdown_framework
@@ -1173,6 +1174,7 @@
   setprop sys.user.0.ce_available ""
   setprop sys.shutdown.requested ""
   setprop service.bootanim.exit ""
+  setprop service.bootanim.progress ""
 
 on userspace-reboot-fs-remount
   # Make sure that vold is running.