title: Jvm heapdump is not generated by signal
body: <p>I noticed that jvm doesn't generated a heap dump by signal 3.
  I tried jvm 1.8.60 and jvm 1.7.60 (ubuntu 14).
  When jvm gets signals it prints thread dump to console but memory dump file doesn't appear.</p>
  
  <p><code>
  java -XX:HeapDumpPath=/tmp/xxx
  </code></p>
  
  <p>Tracing java options confirms that it's all right.</p>
  
  <p><code>
       bool PrintHeapAtSIGBREAK                       = true            {product}<br>
      ccstr HeapDumpPath                             := /tmp/xxx        {manageable}
  </code></p>
  
  <p>What did I miss?</p>
  
  <p>jmap works though.</p>
  
  <p>kill and jvm run under the same user.
  jar is a hello world app.</p>