vlib: clear frame flags on free
vlib: clear frame flags on free

Type: fix

Change-Id: If4a7ac244832ef72d82c71b0277bc110b9500537
Signed-off-by: Stanislav Zaikin <f1cd5a6cdc20dfbb037243d0e9ebf71f42450502@gmail.com>

chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp