Virtual File System (VFS) native memory leak

Implement jboss.vfs.jvmMemLeakPatch environment variable that can be set to performs otherwise redundant zip stream closures to avoid native zlib memory leak due to buggy usage by JDK (bug_id=6735255)[1].

This could reduce process size with the the trade-off possibly a slightly increased heap usage due to having to perform some bookkeeping of streams - holding on to them longer than otherwise.

[1]http://bugs.sun.com/view_bug.do?bug_id=6735255