RFR: 8189102: All tools should support -?, -h and --help

[Lindenmaier, Goetz]

Hi,

please review this change. I also filed a CSR for this:
http://cr.openjdk.java.net/~goetz/wr17/8189102-helpMessage/webrev.02/
Bug: https://bugs.openjdk.java.net/browse/JDK-8189102
CSR: https://bugs.openjdk.java.net/browse/JDK-8191477

See the webrev for a detailed description of the changes.

If required, I'll make break-out changes to be reviewed separately.

I had posted a RFR before, but improved the change to 
give a more complete overview of currently supported flags
for the CSR:
http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-October/028615.html

Best regards,
  Goetz.