Add horizontal add (hadd) vector intrinsic via NEON.
Add horizontal add (hadd) vector intrinsic via NEON.

Having the NEON equivalent of u32x4_hadd for CLIB_HAVE_VEC128

Change-Id: I210f96f7ecb9b80b4753311a68e5e09ccda7e95b
Signed-off-by: Sirshak Das <380db8dd6c2f8c5c272b1de3ca80f9519fdb7fdc@arm.com>
Reviewed-by: Steve Capper <20bdc7169d3cb6e97bf912a5efd111f83cbbb42b@arm.com>
Reviewed-by: Brian Brooks <8e906ed46ccdc37d68771658f0f8f8740a374927@arm.com>
Reviewed-by: Yi He <c1a82badb3a141270d3aafb5824369dd20d94ebb@arm.com>
Verified-by: Lijian Zhang <ada2af69cf641e0319a76fc7a94f297edd147e18@arm.com>

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