RFR(XS): 8203305: PPC64: Improve TM detection for enabling RTM on Linux / POWER9

[Gustavo Romero]

Hi,

Could the following small change be reviewed please?

It improves the TM detection for enabling (or not) RTM on Linux.

With that change JVM uses TM capability flags advertised by the kernel
instead of parsing major/minor kernel version.

That way is better to address TM on POWER9 which now supports a new TM mode
called "TM with no Suspend Mode" and that is not mature yet (so I'm
disabling it for now).

The new mode is just available on POWER9 DD2.1 NV (baremetal) and so TM on
POWER9 VMs behave as on POWER8 hence RTM is enabled on POWER9 VM only.

Nothing changes regarding AIX.

bug:    https://bugs.openjdk.java.net/browse/JDK-8203305
webrev: http://cr.openjdk.java.net/~gromero/POWER9/8203305/v1

Thank you.


Best regards,
Gustavo