RFR (XS): 7036021: G1: build failure on win64 and linux with hs21 in jdk6 build environment

[John Cuthbertson]

Hi Everyone,

Can I have a couple of volunteers to review these changes? The webrev 
can be found at: http://cr.openjdk.java.net/~johnc/7036021/webrev.0/.

Issue: Some of the the changes for 7026932 and 7009266 do cause 
compilation errors when built with the jdk6 build tools. The first is 
missing parentheses around an expression and the second is passing an 
uncasted negative one to a unsigned which has been substituted with 
max_juint.

Thanks,

JohnC