RFR(S): 8160064: StackWalker implementation added logging option without using UL

[Rachel Protacio]

Hi,

Please review this small fix correcting the StackWalker print output 
mechanism by moving it to Unified Logging. Includes a new jtreg test, 
and passes JPRT.

Bug: https://bugs.openjdk.java.net/browse/JDK-8160064
Open webrev: http://cr.openjdk.java.net/~rprotacio/8160064/

Thank you!
Rachel