Load the persistent properties after decrypting the /data partition

Fix for bug 3415286.  The persistent properties are normally read early
in the boot process after /data is mounted.  However, for an encrypted
system, at that point /data is a tmpfs ramdisk.  This change adds a new
command to init (load_persist_props) to read the persistent properties,
and adds an action to init.rc to load the persistent properties.  This
action is triggered by setting a property in vold, but that's in a
different CL.

Change-Id: I74b3057974ee6029c29d956b76fef5566700d471
diff --git a/init/property_service.h b/init/property_service.h
index 045d20a..bc97cc4 100644
--- a/init/property_service.h
+++ b/init/property_service.h
@@ -19,6 +19,7 @@
 
 extern void handle_property_set_fd(void);
 extern void property_init(void);
+extern void load_persist_props(void);
 extern void start_property_service(void);
 void get_property_workspace(int *fd, int *sz);
 extern const char* property_get(const char *name);