net: fix RARP generation

net: fix RARP generation

Due to a mistake operation from me, older version (v10) was merged to
master branch. It's the v11 should be applied. However, the master branch
is not rebase-able. Thus, this patch is made, from the diff between v10
and v11.

The diffs are:

- Add check for parameter and tailroom in rte_net_make_rarp_packet
- Allocate mbuf in rte_net_make_rarp_packet

Besides that, a link error is fixed when shared lib is enabled.

Fixes: 45ae05df824c ("net: add a helper for making RARP packet")
Fixes: c3ffdba0e88a ("vhost: use API to make RARP packet")
Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
Signed-off-by: Yuanhan Liu <yliu@fridaylinux.org>