Add ninja as a native build input for improved build performance

Author: ahojukka5

nix/openpfc/default.nix

@@ -1,7 +1,7 @@
 # SPDX-FileCopyrightText: 2025 VTT Technical Research Centre of Finland Ltd
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-{ lib, stdenv, cmake, mpi, heffte, nlohmann_json, catch2_3 ? null
+{ lib, stdenv, ninja, cmake, mpi, heffte, nlohmann_json, catch2_3 ? null
 , doxygen ? null, version, src, buildType ? "Release", enableDocs ? true
 , enableTests ? true, enableExamples ? true, enableApps ? true }:
 
@@ -15,12 +15,13 @@ stdenv.mkDerivation {
     platforms = lib.platforms.linux;
   };
 
-  nativeBuildInputs = [ cmake ];
+  nativeBuildInputs = [ ninja cmake ];
 
   buildInputs = [ mpi heffte nlohmann_json ] ++ lib.optional enableDocs doxygen
     ++ lib.optional enableTests catch2_3;
 
   cmakeFlags = [
+    "-GNinja"
     "-DCMAKE_BUILD_TYPE=${buildType}"
     "-DOpenPFC_BUILD_TESTS=${if enableTests then "ON" else "OFF"}"
     "-DOpenPFC_BUILD_EXAMPLES=${if enableExamples then "ON" else "OFF"}"