java_lang_Class::array_klass should be array_klass_acquire

Ordering is important for this field. Most reads are done by the compiled code which generate code that maintain dependent loads (see RFR thread)
http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-July/027572.html

The only use for java_lang_Class::array_klass is for printing but should use load acquire for consistency and in case of future use.