[9] RFR (S): 8049355: compiler/rtm/locking/TestRTMLockingThreshold test may fail if transaction was aborted by interrupt

[Filipp Zhinkin]

Hi all,

please take a look at a fix for 8049355.

A few RTM tests verify that method was recompiled if
abort ratio was pretty low. These tests also verify that
before it happened, certain amount of lock attempts was done.

In order to guarantee low abort ratio these tests force abort
at every Nth iteration (every even iter, actually) 
or only once at all.

However, abort may happened on iteration when we're not trying
to force abort (due to CPU interrupt, VMM call, etc.) and amount
of lock attempts may differ from expected value.

To avoid such issue tests were updated to not force abort first
L / 2 iterations and during last L / 2 iterations force it always
(L == RTMLockingThreshold value).

Bug id: https://bugs.openjdk.java.net/browse/JDK-8049355
Webrev: http://cr.openjdk.java.net/~fzhinkin/8049355/webrev.00/
Testing: manual & automated  on host w/ HSW CPU, JPRT

Thanks,
Filipp.