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/keywords.h b/init/keywords.h
index c977fd7..95acd01 100644
--- a/init/keywords.h
+++ b/init/keywords.h
@@ -30,6 +30,7 @@
 int do_chown(int nargs, char **args);
 int do_chmod(int nargs, char **args);
 int do_loglevel(int nargs, char **args);
+int do_load_persist_props(int nargs, char **args);
 int do_wait(int nargs, char **args);
 #define __MAKE_KEYWORD_ENUM__
 #define KEYWORD(symbol, flags, nargs, func) K_##symbol,
@@ -81,6 +82,7 @@
     KEYWORD(chown,       COMMAND, 2, do_chown)
     KEYWORD(chmod,       COMMAND, 2, do_chmod)
     KEYWORD(loglevel,    COMMAND, 1, do_loglevel)
+    KEYWORD(load_persist_props,    COMMAND, 0, do_load_persist_props)
     KEYWORD(ioprio,      OPTION,  0, 0)
 #ifdef __MAKE_KEYWORD_ENUM__
     KEYWORD_COUNT,