8138969: G1CollectorPolicy should use const for applicable methods

[Erik Helin]

Hi all,

this patch adds the keyword const to a lot of methods in
G1CollectorPolicy. This makes it easier to reason about these methods
since they no longer can cause mischief by updating fields in
unpredicted ways.

Enhancement:
https://bugs.openjdk.java.net/browse/JDK-8138969

Webrev:
http://cr.openjdk.java.net/~ehelin/8138969/webrev.00/

Testing:
JPRT

Thanks,
Erik