VPP-308: Added workaround for failed vnet build. For some reason the clock slew is greater with Vagrant 1.8.5 which causes Makefile.am to be timestamped as newer which causes builds to fail.
VPP-308: Added workaround for failed vnet build. For some reason
the clock slew is greater with Vagrant 1.8.5 which causes Makefile.am to be
timestamped as newer which causes builds to fail.

Change-Id: Id0d35c41ac66a2841c5aae20dd678f4bc125e41b
Signed-off-by: Thomas F Herbert <0786393240831fc3b5d6ed63658cfb1f3b1e6c40@redhat.com>

vpp-dev/vpp,milanlenco/vpp,GabrielGanne/vpp-flowtable,vpp-dev/vpp,FDio/vpp,milanlenco/vpp,FDio/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,FDio/vpp,FDio/vpp,vpp-dev/vpp,milanlenco/vpp,milanlenco/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,milanlenco/vpp,vpp-dev/vpp,GabrielGanne/vpp-flowtable,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,milanlenco/vpp,vpp-dev/vpp,GabrielGanne/vpp-flowtable,vpp-dev/vpp,chrisy/vpp