RFRF: 8043936 Drop HPROF as demo, keep as HPROF agent shipped with JDK

[Staffan Larsen]

Please review the following change to remove hprof as part of the demo package. Instead, the source code has been moved to the jdk.hprof.agent module.

bug: https://bugs.openjdk.java.net/browse/JDK-8043936
webrev: http://cr.openjdk.java.net/~sla/8043936/webrev.00/

Thanks,
/Staffan