Review Request CR#7118743 : Alternative Hashing for String with Hash-based Maps

[Doug Lea]

Note that ConcurrentHashMap has been overhauled for JDK8.
The preliminary version, partially waiting for stability
on lambda-related stuff, has been out a while as
jsr166e.ConcurrenthashMapV8 (see
http://gee.cs.oswego.edu/dl/concurrency-interest/index.html)

It is easy to add seeded murmur hash code to this,
which I plan to do. One question:

Given the JDK8 conventions in your mail,
it seems that field hashMask can never be zero,
so doesn't need to be checked, but is in your JDK8 diffs:
   int h = hashMask;
   if ((0 != h) && (k instanceof String)) {
         return ((String) k).hash32() ^ h;

... and further simplifying a bit from there.

(Also "hashMask" seems like an odd name for this. "hashSeed"?)

-Doug