[11u] RFR (S) 8223444: Improve CodeHeap Free Space Management

[Dmitry Chuyko]

Hello,

Original RFE: https://bugs.openjdk.java.net/browse/JDK-8223444
Original post-fix: https://bugs.openjdk.java.net/browse/JDK-8231460

Original patch applies almost cleanly except 4 changes in 
CodeHeap::add_to_freelist because JDK-8238356 is already backported, 
they were applied manually.
Original post-fix (for performance issue) applies cleanly.

11u webrev: http://cr.openjdk.java.net/~dchuyko/8223444/webrev.11u.00/

Testing: tier1, tier2.

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Thanks,
-Dmitry