netmap_vale_attach can leak memory references
netmap_vale_attach can leak memory references

If netmap_vale_attach() is called with a memory region, it
will leak a reference to that region.  Make sure to do a
netmap_mem_put in this case.  Fixed issue 559

luigirizzo/netmap,luigirizzo/netmap,luigirizzo/netmap,luigirizzo/netmap,luigirizzo/netmap