RFR(XS): 8223968: Add abort type description to RTM statistic counters

[Gustavo Romero]

Hi,

Could the following change be reviewed please?

Bug   : https://bugs.openjdk.java.net/browse/JDK-8223968
Webrev: http://cr.openjdk.java.net/~gromero/8223968/v1/

It simply adds a description to the RTM abort counters, helping to understand
the RTM statistics output faster and better.

The change touches RTM shared code and also RTM tests in order to adapt the
regex to the new output format.

Thanks a lot.

Best regards,
Gustavo