internal/netlink: export generic connection

This enables abstractions around some families to be implemented in a separate package.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/netlink/netlink_test.go

@@ -7,7 +7,7 @@ import (
 
 type payloadTestCase struct {
 	name string
-	f    func(c *conn)
+	f    func(c *Conn)
 	want []byte
 }
 
@@ -21,7 +21,7 @@ func checkPayload(t *testing.T, testCases []payloadTestCase) {
 			t.Parallel()
 			t.Helper()
 
-			c := conn{port: 1, pos: syscall.NLMSG_HDRLEN}
+			c := Conn{port: 1, pos: syscall.NLMSG_HDRLEN}
 			tc.f(&c)
 			if got := c.pending(); string(got) != string(tc.want) {
 				t.Errorf("pending: %#v, want %#v", got, tc.want)