RFR: 8137164: Include PID in the JFR jcmd hint

[Erik Gahlin]

Hi,

Could I have review of the following fix that adds the PID to the output 
when starting a JFR recording.

Webrev:
http://cr.openjdk.java.net/~egahlin/8137164/

Bug:
https://bugs.openjdk.java.net/browse/JDK-8137164

Testing:
test/jdk/jdk/jfr/*

Thanks
Erik