RFR(S): 8166931: Do not include classes which are unusable during run time in the classlist file

[Calvin Cheung]

Please review this small fix for not including classes in the classlist 
file which are unusable during run time.

bug: https://bugs.openjdk.java.net/browse/JDK-8166931

webrev: http://cr.openjdk.java.net/~ccheung/8166931/webrev.00/

Testing:
     JPRT with -testset hotspot
     jtreg tests under hotspot/runtime on all supported platforms (in 
progress)

thanks,
Calvin