RFR 8214442: Improve stack walk API by adding handle marks

[Harold David Seigel]

Hi,

Please review this small JDK-13 change to add handle marks to the stack 
walk API for reasons described in the bug.

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8214442/webrev/index.html

JBS Bug:  https://bugs.openjdk.java.net/browse/JDK-8214442

The fix was regression tested by running Mach5 tiers 1 and 2 tests and 
builds on Linux-x64, Windows, and Mac OS X, Mach5 tiers 3 -5 o 
Linux-x64, and by running JCK-12 Lang and VM tests on Linux-x64.

Thanks, Harold