Call markBootAttempt when serice manager available

This causes adds a call the fucntion to decrement the
checkpoint's retry count as soon as service manager is
available.

Test: vdc setCheckpoint 2 then reboot 3 times checking state
Bug: 112901762
Change-Id: Ie0a78b1eb05b340718e76175509d1ebefae68017
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 9aaad8f..21d234f 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -336,6 +336,8 @@
     start servicemanager
     start hwservicemanager
     start vndservicemanager
+    start vold
+    exec - system system -- /system/bin/vdc checkpoint markBootAttempt
 
     # Once everything is setup, no need to modify /.
     # The bind+remount combination allows this to work in containers.