RFR(xs): 8195000: Clean out left-overs in arguments.hpp

[Per Liden]

Hi,

The refactoring done in JDK-8189171 moved some functions out from 
Arguments to separate classes, but the function declarations were left. 
These should just be removed.

Bug: https://bugs.openjdk.java.net/browse/JDK-8195000
Webrev: http://cr.openjdk.java.net/~pliden/8195000/webrev.0/

/Per