routing: cjdns: Wno-overread warning removed if toolchain lower than version 11

Added condition to remove -Wno_overread warning if toolchain is lower than version 11, based on recommendation (https://github.com/NixOS/nixpkgs/pull/168997) Added two patches from openwrt stream. patch3.10 (1df5290b92625823bb9725a5406383116463f3ac) invalid-pointer (d710a7938977c84d6ea0f74b21dc50111e5e968c)