testenv: Check for /sys/fs/bpf mount in root namespace

We mention in basic04 that the testenv does this, so better make sure it
does :)

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: tohojo

testenv/testenv.sh

@@ -202,6 +202,10 @@ setup()
 
     CLEANUP_FUNC=cleanup_setup
 
+    if ! mount | grep -q /sys/fs/bpf; then
+        mount -t bpf bpf /sys/fs/bpf/
+    fi
+
     ip netns add "$NS"
     ip link add dev "$NS" type veth peer name "$PEERNAME"
     OUTSIDE_MAC=$(iface_macaddr "$NS")