RFR (S): 8078669: G1 applies SurvivorAlignmentInBytes to both survivor and old gen

[Thomas Schatzl]

Hi all,

  can I have reviews for the following small fix: since JDK-8060025
survivor alignment has been applied to both survivor and old gen regions
(if enabled of course).

This has gone unnoticed, because the tests somehow detected that in this
situation everyhing is fine due to "someone else that allocated
objects".

The change fixes the problem (in g1Allocator.hpp), and removes this
strange bailout in the tests, at the same time disabling PLAB resizing
which causes too much wasted space (extra allocation) that otherwise
causes the test to fail.

CR:
https://bugs.openjdk.java.net/browse/JDK-8078669

Webrev:
http://cr.openjdk.java.net/~tschatzl/8078669/webrev/

Testing:
no performance changes in object copy times, several JPRT runs in the
process, making sure there are no failures.

Thanks,
  Thomas