On Linux 5.4, build WireGuard from backports. Linux 5.10 contains
wireguard in-tree.
Add in-kernel crypto libraries required by WireGuard along with
arch-specific optimizations.
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
(cherry picked from commit 06351f1bd0455abacb700db5098bb798f66948fc)
(cherry picked from commit 464451d9ab824c2ed62f7da33f0a965f562714c8)