RFR(xs): 8150619: Improve thread based logging introduced with 8149036

[Thomas Stüfe]

Hi all,

please review and sponsor this tiny addition to 8149036. These are some
tiny cleanups which could not be added to the original change anymore
because it was already pushed.

bug: https://bugs.openjdk.java.net/browse/JDK-8150619
webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8150619-addon-to-thread-logging/webrev.00/webrev/index.html

Original mail thread for 8149036:
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2016-February/018099.html

The change unifies the logging messages for all platforms and all log sites
as much as possible.

Please note: "tid" always refers to whatever os::current_thread_id()
returns. This may be a pthread_t (AIX, BSD), a kernel thread id or similar
(Mac, Linux, Solaris), or a windows thread id. Beside printing the "tid", I
print out additional thread ids where it may be interesting, especially at
thread start and attach. On AIX, I print the kernel thread id, on
Linux/Mac, the pthread id.

There are some instances where I have only one and not the other:
- after a call to pthread_create(), I only have the pthread id of the
newborn thread, not the kernel thread id, so this is all I can print.
- in shared code, all I have or all I can print without making the code to
complicated is the "tid"

Finally, the change adds a jtreg test to logging, to test the new logging
switches.

Thanks & Kind Regards, Thomas