cmake: fix the build WITH_DPDK=ON

cmake: fix the build WITH_DPDK=ON

* add Findcryptopp.cmake back
  cryptopp support was dropped in #20015, but it's required by
  src/msg/async/dpdk/TCP.h, which `#include <cryptopp/md5.h>`
  so, to fix the FTBFS of WITH_DPDK=ON, we need to bring
  Findcryptopp.cmake back. it was also removed in #20015.
* pass "-march=core2" when building sources which include dpdk headers.
  i was wrong that the headers shipped by distro are generic.
  the headers use the sse instructions for speedup memcpy, see
  /usr/include/x86_64-linux-gnu/dpdk/rte_memcpy.h .
* also, we need to include the arch specific include directory
  for building with dpdk.

Signed-off-by: Kefu Chai <kchai@redhat.com>