RFR(xs) 8231606: _method_ordering is not set during CDS dynamic dump time

[Calvin Cheung]

bug: https://bugs.openjdk.java.net/browse/JDK-8231606

webrev: http://cr.openjdk.java.net/~ccheung/8231606/webrev.00/

A small fix for setting up the _method_ordering field during CDS dynamic 
dumping.

Testing: tier1 - 3.

thanks,

Calvin