This enables building WolfSSL with Curve448, which can be used by Strongswan. This has been tested on a Linksys E8450, running OpenWrt 22.03-rc4. This allows parity with OpenSSL, which already supports Curve448 in OpenWrt 21.02. Fixes openwrt/packages#18812. Signed-off-by: Joel Low <joel@joelsplace.sg>