Add a metadata folder for libsnapshot.

/metadata/ota will store the update state ("none", "applying",
"booting", "merging") for each dynamic partition. The data will be
managed by libsnapshot, whose primary consumer will be update_engine
but will also be available to recovery/fastbootd.

Bug: 136678799
Test: /metadata/ota exists
Change-Id: I3e06484cafeb363904914767abc8984adaa37021
diff --git a/rootdir/init.rc b/rootdir/init.rc
index a5bfc41..baed2f4 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -409,6 +409,7 @@
     mkdir /metadata/vold
     chmod 0700 /metadata/vold
     mkdir /metadata/password_slots 0771 root system
+    mkdir /metadata/ota 0700 root system
 
     mkdir /metadata/apex 0700 root system
     mkdir /metadata/apex/sessions 0700 root system