8079200: Fix heapdump tests to validate heapdump after jhat is removed

[Yekaterina Kantserova]

Hi,

Could I please have a review of this fix.
bug: https://bugs.openjdk.java.net/browse/JDK-8079200
webrev: http://cr.openjdk.java.net/~ykantser/8079200/webrev.00

The fix makes sure the HprofParser is available for all types of test 
frameworks, not only JTreg. It will be a part of test-lib.jar.

Thanks,
Katja