8072856: Eliminate ProcessTools.getProcessId dependency on sun.management.VMManagement

[Yekaterina Kantserova]

Hi,

Could I please have a review of this small fix.

bug: https://bugs.openjdk.java.net/browse/JDK-8072856
webrev: http://cr.openjdk.java.net/~ykantser/8072856/webrev.00/

Thanks,
Katja