openvswitch: add patch for adding KCFLAGS var to the OVS build

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
openvswitch: add KCFLAGS="-Wno-error=date-time" to kernel modules build

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Merge pull request #477 from commodo/openvswitch-gcc-4.9

OpenVswitch GCC 4.9 build fix