RFR(xxs): 8144702: Using tid decorator in Unified Logging may crash VM

[Thomas Stüfe]

Hi all,

please review this tiny fix:

webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8144702-Using-tid-decorator-in-Unified-Logging-may-crash-VM/webrev.00/webrev/
bug: https://bugs.openjdk.java.net/browse/JDK-8144702

Unified Logging uses Thread::current() when printing out the "tid"
decorator, which will crash the VM if logging is done after thread start
and before thread TLS slot initialization or after thread TLS slot cleanup
and before thread finish.

Kind regards, Thomas