RFR: 8252108: Modify nsk/stress/stack tests to check page size

[Nick Gasson]

Hi,

Bug: https://bugs.openjdk.java.net/browse/JDK-8252108
Webrev: http://cr.openjdk.java.net/~ngasson/8252108/webrev.1/

As discussed on the review thread for JDK-8251490 [1], it's better to
have these tests enabled conditionally on 4K page size, rather than
always disabled on AArch64, since the original issue was only present on
AArch64 systems configured with 64K pages.

Added a new "vm.pageSize" jtreg property that can be used in @requires.

stack018.java intermittently times out with the increased -Xss448K so
I've lowered this to -Xss220k and added @requires vm.pageSize ==
4096 (the original value -Xss200k fails with "Maximal recursion depth:
0" on AArch64 fastdebug build).

[1] https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2020-August/041299.html

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Thanks,
Nick