Setting DPDK_PMD_TAP=y when building will enable the tap PMD
in the build configuration that is generated for DPDK. Enabling
this currently results in a failure during compilation because
rte_gso.h is not found. RTE_LIBRTE_GSO needs to be set to y for
this to work.
Use the setting for the tap PMD to determine the value for
RTE_LIBRTE_GSO.
Change-Id: Ie395417b1c62369a95320856081ad52c674ce9f2
Signed-off-by: Matthew Smith <mgsmith@netgate.com>