When deleting a memif interface, there is a memory leak in
mif->local_disc_string. The code that leads to memory leak is
memif_delete_if -> memif_disconect -> vec_dup
Type: fix
Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: I579c743c3d47770131153e083e65f6cd899067b3