acinclude: Autodetect DPDK location when configuring OVS

acinclude: Autodetect DPDK location when configuring OVS

When using DPDK datapath, the OVS configure script requires the DPDK
build directory passed on --with-dpdk. This can be avoided if DPDK
library, headers are in standard compiler search paths.

This patch fixes the problem by searching for DPDK libraries in standard
locations and configure OVS sources for dpdk datapath.

If the install location is manually specified in "--with-dpdk"
autodiscovery shall be skipped.

Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>