RFR: 8076473 Remove the jhat code and update makefiles

[Staffan Larsen]

Please review this change to remove the jhat tool. I will not push this change until the tests have been removed (see a different review thread).

JEP: https://bugs.openjdk.java.net/browse/JDK-8059039 <https://bugs.openjdk.java.net/browse/JDK-8059039> 
bug: https://bugs.openjdk.java.net/browse/JDK-8076473 <https://bugs.openjdk.java.net/browse/JDK-8076473>

webrev root: http://cr.openjdk.java.net/~sla/8076473/webrev.root.00/ <http://cr.openjdk.java.net/~sla/8076473/webrev.root.00/>
webrev jdk: http://cr.openjdk.java.net/~sla/8076473/webrev.jdk.00/ <http://cr.openjdk.java.net/~sla/8076473/webrev.jdk.00/>

Thanks,
/Staffan