RFR: JDK-8207365: Make man pages optional

[Erik Joelsson]

Hello,

The man pages are currently not being actively maintained by anyone, so 
we would like to make including them in the build optional. Oracle 
produced builds will disable inclusion of man pages. (This was already 
the case for OracleJDK builds but will now also be true for Oracle 
produced OpenJDK builds)

The patch adds a configure parameter 
--enable-manpages/--disable-manpages, default is enabled, just like 
before the change. The patch also changes the Oracle configuration in 
jib-profiles.js to disable manpages.

Bug: https://bugs.openjdk.java.net/browse/JDK-8207365

Webrev: http://cr.openjdk.java.net/~erikj/8207365/webrev.01/index.html

/Erik