RFR: 8235427: Remove unnecessary parameters from G1CollectedHeap::free_region and HeapRegion::hr_clear

[Stefan Johansson]

Hi,

Please review this cleanup to get rid of some unnecessary boolean passing.

Issue: https://bugs.openjdk.java.net/browse/JDK-8235427
Webrev: http://cr.openjdk.java.net/~sjohanss/8235427/00/

Summary
While reviewing the fix for JDK-8165443 we realized that some boolean 
parameters passed to G1CollectedHeap::free_region always had the same 
values and could therefore be removed. When looking a bit closer it 
turns out even more parameters can be skipped.

The two things that are really changed when it comes to functionality in 
this patch are:
1. When freeing the CSet we previously always cleared the hot card cache 
for old regions. We now rely on this being done by free_region and this 
will have the effect that for evacuation failures we won't clear the hot 
card cache for those regions having failures. I've discussed this with a 
couple of others and we can't see any problems with this.

2. When creating heap regions we previously used the default value false 
for locked when initializing heap regions, but we know this code path 
will never be called in parallel so we can safely remove this parameter 
and always do rem_set()->clear_locked() in hr_clear().

Testing
Mach5 tier1-3 passed, currently running tier4-5 as well.

Cheers,
Stefan