init.rc: create /data/misc/reboot owned by system

Directory will be read and modified by system uid.

Bug: 37251463
Test: Manual: reboot and inspect
Change-Id: I76212f65af991ff9ad0969b9c0b8460b80fb9cd2
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 0b3e3ee..a440b7a 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -407,7 +407,7 @@
     mkdir /data/misc/boottrace 0771 system shell
     mkdir /data/misc/update_engine 0700 root root
     mkdir /data/misc/trace 0700 root root
-    mkdir /data/misc/reboot 0700 root root
+    mkdir /data/misc/reboot 0700 system system
     # profile file layout
     mkdir /data/misc/profiles 0771 system system
     mkdir /data/misc/profiles/cur 0771 system system