Fuse platform build fails on Windows during mq/mq-assembly/jboss-a-mq step

The fuse builds fails on Jenkins on Windows during the fuse-platform build in mq/mq-assembly/jboss-a-mq. The maven-assembly--plugin fails because there are no windows specific assembly descriptors.

Since we don't actually need to build on windows, we can just exclude this paft of the build when running on windows.