internal/netlink: enlarge recvfrom buffer

This also uses an array type for the buffer since its size now uses the hardcoded value found in the kernel.

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

internal/netlink/netlink_test.go

@@ -1,7 +1,6 @@
 package netlink
 
 import (
-	"os"
 	"syscall"
 	"testing"
 )
@@ -23,10 +22,7 @@ func checkPayload(t *testing.T, testCases []payloadTestCase) {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
-			c := conn{
-				pos: syscall.NLMSG_HDRLEN,
-				buf: make([]byte, os.Getpagesize()),
-			}
+			c := conn{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)