RFR: JDK-8133669 - Remove unused code in Arguments

[Jesper Wilhelmsson]

Hi,

Please review this small removal of unused code in the argument parser. The 
variables Arguments::_min_heap_free_ratio and Arguments::_max_heap_free_ratio 
have no use after the flag verification changes. They can be removed together 
with Arguments::post_after_ergo_constraint_check() that is used to update them.

Bug: https://bugs.openjdk.java.net/browse/JDK-8133669
Webrev: http://cr.openjdk.java.net/~jwilhelm/8133669/webrev.00/

Thanks,
/Jesper