In JDK-6515172 code was added that allows for dynamic CPU_SET support for systems with > 1024 processors. While compiler/runtime support for this has been around for a few years now there is still some use of of older build platforms out in the broader OpenJDK community. This change will allow the CPU_ALLOC related code to be skipped if not supported at build time.

This change will also allow for a almost* direct backport to JDK 8u, where the official build platforms also do not support this feature.

* The logging statements will have to be changed or deleted.