udp: make udp encap pool cacheline aligned
udp: make udp encap pool cacheline aligned

This fixes issue with unaligned vector access on gcc-7.
As udp_encap_t is declared as cacheline aligned, alloc also need to be.

Change-Id: Ic30876911baf2c22c135097490075fa7bcf0ca18
Signed-off-by: Damjan Marion <9141bba8b2efed526e55cf796d48631af330ad98@cisco.com>

FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp