rte_pktmbuf_free_bulk() calls __rte_mbuf_sanity_check(), which behaves
differently depending on RTE_LIBRTE_MBUF_DEBUG being defined or not.

Unfortunately, rte_pktmbuf_free_bulk() is not inline, but in the C file.
This means that the behavior of __rte_mbuf_sanity_check() within
rte_pktmbuf_free_bulk() is controlled by the RTE_LIBRTE_MBUF_DEBUG setting when
building the DPDK library, not when building the application.

rte_pktmbuf_free_bulk() should have been inline in the header file, so the
application developer can control its __rte_mbuf_sanity_check() behavior by
using RTE_LIBRTE_MBUF_DEBUG setting when building the application.

How to remove this function from the ABI and make it inline instead?