To build with go1.19, gvisor needs
99325baf ("Bump gVisor build tags to go1.19").
However gvisor.dev/gvisor/pkg/tcpip/buffer is no longer available,
so refactor to use gvisor.dev/gvisor/pkg/tcpip/link/channel directly.
Signed-off-by: Shengjing Zhu <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
