Remove user_map.h; replace with a header at the beginning of the user-space...

Remove user_map.h; replace with a header at the beginning of the user-space blob.  User work queue no started by os_brinup() on behalf of the application

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5727 42af7a65-404d-4744-a932-0658087f49c3