fastd: fix build on aarch64

pkgs/tools/networking/fastd/default.nix

@@ -1,5 +1,16 @@
-{ lib, stdenv, fetchFromGitHub, bison, meson, ninja, pkg-config
-, libuecc, libsodium, libcap, json_c, openssl }:
+{ lib
+, stdenv
+, fetchFromGitHub
+, bison
+, meson
+, ninja
+, pkg-config
+, libuecc
+, libsodium
+, libcap
+, json_c
+, openssl
+}:
 
 stdenv.mkDerivation rec {
   pname = "fastd";
@@ -12,8 +23,27 @@ stdenv.mkDerivation rec {
     sha256 = "1p4k50dk8byrghbr0fwmgwps8df6rlkgcd603r14i71m5g27z5gw";
   };
 
-  nativeBuildInputs = [ pkg-config bison meson ninja ];
-  buildInputs = [ libuecc libsodium libcap json_c openssl ];
+  nativeBuildInputs = [
+    bison
+    meson
+    ninja
+    pkg-config
+  ];
+
+  buildInputs = [
+    json_c
+    libcap
+    libsodium
+    libuecc
+    openssl
+  ];
+
+  # some options are only available on x86
+  mesonFlags = lib.optionals (!stdenv.isx86_64 && !stdenv.isi686) [
+    "-Dcipher_salsa20_xmm=disabled"
+    "-Dcipher_salsa2012_xmm=disabled"
+    "-Dmac_ghash_pclmulqdq=disabled"
+  ];
 
   enableParallelBuilding = true;