util: replace body of virNetDevMacVLanDelete() with virNetlinkDelLink()

These two functions are identical, so no sense in having the
duplication. I resisted the temptation to replace calls to
virNetDevMacVLanDelete() with calls to virNetlinkDelLink() just in
case some mythical future platform has macvtap devices that aren't
managed with netlink (or in case we some day need to do more than just
tell the kernel to delete the device).

src/util/virnetdevmacvlan.c

 /*
- * Copyright (C) 2010-2014 Red Hat, Inc.
+ * Copyright (C) 2010-2015 Red Hat, Inc.
  * Copyright (C) 2010-2012 IBM Corporation
  *
  * This library is free software; you can redistribute it and/or
@@ -220,70 +220,7 @@ virNetDevMacVLanCreate(const char *ifname,
  */
 int virNetDevMacVLanDelete(const char *ifname)
 {
-    int rc = -1;
-    struct nlmsghdr *resp = NULL;
-    struct nlmsgerr *err;
-    struct ifinfomsg ifinfo = { .ifi_family = AF_UNSPEC };
-    unsigned int recvbuflen;
-    struct nl_msg *nl_msg;
-
-    nl_msg = nlmsg_alloc_simple(RTM_DELLINK,
-                                NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL);
-    if (!nl_msg) {
-        virReportOOMError();
-        return -1;
-    }
-
-    if (nlmsg_append(nl_msg,  &ifinfo, sizeof(ifinfo), NLMSG_ALIGNTO) < 0)
-        goto buffer_too_small;
-
-    if (nla_put(nl_msg, IFLA_IFNAME, strlen(ifname)+1, ifname) < 0)
-        goto buffer_too_small;
-
-    if (virNetlinkCommand(nl_msg, &resp, &recvbuflen, 0, 0,
-                          NETLINK_ROUTE, 0) < 0) {
-        goto cleanup;
-    }
-
-    if (recvbuflen < NLMSG_LENGTH(0) || resp == NULL)
-        goto malformed_resp;
-
-    switch (resp->nlmsg_type) {
-    case NLMSG_ERROR:
-        err = (struct nlmsgerr *)NLMSG_DATA(resp);
-        if (resp->nlmsg_len < NLMSG_LENGTH(sizeof(*err)))
-            goto malformed_resp;
-
-        if (err->error) {
-            virReportSystemError(-err->error,
-                                 _("error destroying %s interface"),
-                                 ifname);
-            goto cleanup;
-        }
-        break;
-
-    case NLMSG_DONE:
-        break;
-
-    default:
-        goto malformed_resp;
-    }
-
-    rc = 0;
- cleanup:
-    nlmsg_free(nl_msg);
-    VIR_FREE(resp);
-    return rc;
-
- malformed_resp:
-    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                   _("malformed netlink response message"));
-    goto cleanup;
-
- buffer_too_small:
-    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                   _("allocated netlink buffer is too small"));
-    goto cleanup;
+    return virNetlinkDelLink(ifname);
 }