RFR(S) 8154745: Move default G1 pause time target setup to argument parsing

[Erik Helin]

On 2016-04-20, Mikael Gerdin wrote:
> Hi all,
> 
> Please review this fairly small change to move even more code out of
> G1CollectorPolicy.
> The policy has previously initialized and validated MaxGCPauseMillis and
> GCPauseIntervalMillis in its constructor.
> 
> This should be moved to Arguments::set_g1_gc_flags, where other default
> values of globally known flags are set.
> We can then move the constraint checking to the proper command line flag
> constraint functions (pause interval > pause target and setting pause
> interval without setting pause target) and modify the constraints so that
> they are applied before the GC subsystem is initialized (by changing
> AfterMemorInit to AfterErgo)
> 
> I also took the liberty to correct the comment I copied to correctly state
> that we set up the pause interval based on the pause time target, not the
> other way around.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8154745
> Webrev: http://cr.openjdk.java.net/~mgerdin/8154745/webrev.0

Looks good, Reviewed.

Thanks,
Erik

> Testing: RBT GC Testing
> 
> /Mikael