arb: 2.21.1 -> 2.22.1, enable parallel building

pkgs/development/libraries/arb/default.nix

@@ -9,13 +9,13 @@
 
 stdenv.mkDerivation rec {
   pname = "arb";
-  version = "2.21.1";
+  version = "2.22.1";
 
   src = fetchFromGitHub {
     owner = "fredrik-johansson";
     repo = pname;
     rev = version;
-    sha256 = "sha256-OBY2gKVnvrZLVrv+d6rXQLo026mrGB9eyNV4LESgrNI=";
+    sha256 = "sha256-Xd3dy7zr4i3pULLFOYtedpS5Yj9Ljwyu6r4kfhRynmE=";
   };
 
   buildInputs = [ mpir gmp mpfr flint ];
@@ -27,6 +27,8 @@ stdenv.mkDerivation rec {
     "--with-flint=${flint}"
   ];
 
+  enableParallelBuilding = true;
+
   doCheck = true;
 
   meta = with lib; {