RFR(XS): [8u] Cleanup: Removed redundant ClassLoaderData::clear_claimed_marks()

[Zhengyu Gu]

Cleanup for jdk8u.

Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/clean_cld_8u/webrev.00/

Test:

   hotspot_gc_shenandoah with fastdebug and release builds.


Thanks,

-Zhengyu