RFR: JDK-8219475: javap man page needs to be updated

[Jonathan Gibbons]

Please review a small change for the javap command-line help.

A place-holder Option is added for -J, so that it is included in the 
command-line help. The option itself is handled by the launcher.

Some dead-code, in JavapTask:953, is also removed, since there are no 
options whose primary name is `-h` or `-verify`.  (`-h` exists, but is 
just a synonym for `--help`, and `-verify` went away a long time ago.)

In the properties file, a duplicate entry for `main.usage.summary` is 
also removed.

-- Jon

JBS: https://bugs.openjdk.java.net/browse/JDK-8219475
Webrev: http://cr.openjdk.java.net/~jjg/8219475/webrev/