VPP-1332 memif: add/del socket filename bugfix
VPP-1332 memif: add/del socket filename bugfix

in case of relative path, create subdirs inside runtime dir.
in case of absolute path, if folder does not exist return error.

Change-Id: I01fe018102c69deb105160cfa18b741541d76c82
Signed-off-by: Jakub Grajciar <80f619e109c6efd382b3a6accd36cbd33d9669a2@cisco.com>

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