UnsafeStaticFieldAccessorImpl#base should be final

Originally posted by Peter Levart at core-libs-dev@
http://mail.openjdk.java.net/pipermail/core-libs-dev/2012-November/012498.html

This is potentialiy severe issue since the FieldAccessors can be published via the race, which makes it unsafe to have non-final/non-volatile fields exposed in FieldAccessor. Peter had proposed a very simple fix:
http://dl.dropbox.com/u/101777488/jdk8-hacks/UnsafeStaticFieldAccessorImpl.base/webrev/index.html