RFR(S): 8203669: PPC64: Fix jtreg RTM tests after "8203305: Improve TM detection for enabling RTM on Linux / POWER9"

[Gustavo Romero]

Hi,

Could the following small fix be reviewed please?

It touches shared code.

bug:    https://bugs.openjdk.java.net/browse/JDK-8203669
webrev: http://cr.openjdk.java.net/~gromero/POWER9/8203669

Since change "8203305: Improve TM detection for enabling RTM on Linux / POWER9"
JVM on PPC64 is not advertising anymore the feature "tcheck" which indicated
that RTM was supported by the JVM in case both CPU and OS supported hardware
transactional memory.

It happens that several tests under /test/hotspot/jtreg/compiler/rtm rely on the
JVM to advertise if RTM is supported by the JVM on a given CPU/OS and so they
were failing to be skipped (or not) on different PPC64/Linux combinations.

That change fixes it by re-introducing a feature to inform that RTM is supported
by the JVM when appropriated (given valid OS/CPU support) and now it does it by
advertising that feature as on x86_64, reporting the feature as "rtm".

It also incorporates a check for when OS does not support RTM but CPU does in
test:

TestUseRTMLockingOptionOnUnsupportedCPU.java.

Just on PPC64 it might be the case that although CPU supports RTM (HTM)
instructions the OS version might not support it, like on old kernels that do
not abort transactions on syscalls. JVM correctly reports each case so the test
was adapted to test them.

That change also corrects a couple of nit typos elsewhere not related to
"8203305".


Thank you.

Best regards,
Gustavo