RFR: 8029630: Print thread id hex representation in error messages.

[Max Ockner]

Hello,
Please review this change:

Bug:  https://bugs.openjdk.java.net/browse/JDK-8029630
Webrev: http://cr.openjdk.java.net/~mockner/8029630.2/
Summary: Existing error messages for vm crashes print the decimal 
representation of the current thread id. The message format has been 
changed to print the hex value of the thread id.

Tested with jtreg runtime to make sure nothing was broken. I tested the 
new functionality separately. I crashed the vm and examined the debugger 
output to make sure the hexadecimal thread id printed in the error 
message matched one of the threads listed by the debugger.

Thanks,
Max