const golang.org/x/sys/unix.RTNLGRP_TUNNEL

one use

	golang.org/x/sys/unix (current package)
		ztypes_linux.go#L3119: 	RTNLGRP_TUNNEL        = 0x23

The pages are generated with Golds v0.7.6. (GOOS=linux GOARCH=amd64)