ensure Thread::flags is always updated atomically

Since this field is sometimes updated from other threads, it is
essential that we always update it atomically.
Merge pull request #329 from dicej/atomic-flags

ensure Thread::flags is always updated atomically
Enable individual platform/arch builds by watching for platform/arch
Merge pull request #330 from sgoings/master

Enable individual platform/arch builds by watching for platform/arch
change classpath artifact name to 'classpath-avian' and remove c++ sources from it
move binaryToObject to a 'tools' artifact
automagically detect java_home in gradle
adjust gradle publish coordinates
fix gradle macosx OperatingSystem naming
use avian classpath built with gradle
(fixup) fix zip test
(fixup) fix jdk-test
(fixup) fix bootimage build
(fixup) classpath-avian rename fix
generate openjdk jar from gradle