Request for review: 7102776 Pack instanceKlass boolean fields into single u1 field

[Jiangli Zhou]

Compact following 4 instanceKlass boolean fields into a signal u1 field. 
Each flag now uses 1-bit. The new field is placed after the 
_idnum_allocated_count field to utilize the unused 2-byte after 
_idnum_allocated_count. Compacting these fields saves 4-bytes for each 
loaded classes.

   bool _is_marked_dependent; // used for marking during flushing and
   deoptimization
   bool _rewritten; // methods rewritten.
   bool _has_nonstatic_fields; // for sizing with UseCompressedOops
   bool _should_verify_class; // allow caching of preverification

http://cr.openjdk.java.net/~bobv/7102776/webrev.00/

Tested with runThese on ubuntu. Ran JPRT.

Thanks,
Jiangli