libxl: fix double free of ifname, when makes args for qemu.

libxl: fix double free of ifname, when makes args for qemu.

In libxl_build_device_model_args_new, vifs[i].ifname can be free two
times, by the gc, and by freeing the vifs structures. This patch avoids
this.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
committer: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 tools/libxl/libxl.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)