libxl: write vifname in xenstore if set.

Simple fix to enable user to specify vif names.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell.com>
xen-unstable changeset: 24459:caf9753d4cc1
Backport-requested-by: Roderick Colenbrander <thunderbird2k@xxxxxxxxx>
Signed-off-by: Giam Teck Choon <giamteckchoon@xxxxxxxxx>


diff -urN a/tools/libxl/libxl.c b/tools/libxl/libxl.c
--- a/tools/libxl/libxl.c       2012-03-14 00:49:03.000000000 +0800
+++ b/tools/libxl/libxl.c       2012-03-14 01:34:28.000000000 +0800
@@ -1229,6 +1229,12 @@
     flexarray_append(back, libxl__sprintf(&gc, "%d", 1));
     flexarray_append(back, "script");
     flexarray_append(back, nic->script);
+
+    if (nic->ifname) {
+       flexarray_append(back, "vifname");
+       flexarray_append(back, nic->ifname);
+    }
+
     flexarray_append(back, "mac");
     flexarray_append(back, libxl__sprintf(&gc, "%02x:%02x:%02x:%02x:%02x:%02x",
                                                  nic->mac[0], nic->mac[1], nic->mac[2],