Merge pull request #192906 from OPNA2608/fix/openblas-parallelism

pkgs/development/libraries/science/math/openblas/default.nix

···
     buildPackages.stdenv.cc
   ];
 
+  enableParallelBuilding = true;
+
   makeFlags = mkMakeFlagsFromConfig (config // {
     FC = "${stdenv.cc.targetPrefix}gfortran";
     CC = "${stdenv.cc.targetPrefix}${if stdenv.cc.isClang then "clang" else "cc"}";
···
     NO_BINARY_MODE = if stdenv.isx86_64
         then toString (stdenv.hostPlatform != stdenv.buildPlatform)
         else stdenv.hostPlatform != stdenv.buildPlatform;
+    # This disables automatic build job count detection (which honours neither enableParallelBuilding nor NIX_BUILD_CORES)
+    # and uses the main make invocation's job count, falling back to 1 if no parallelism is used.
+    # https://github.com/xianyi/OpenBLAS/blob/v0.3.20/getarch.c#L1781-L1792
+    MAKE_NB_JOBS = 0;
   } // (lib.optionalAttrs singleThreaded {
     # As described on https://github.com/xianyi/OpenBLAS/wiki/Faq/4bded95e8dc8aadc70ce65267d1093ca7bdefc4c#multi-threaded
     USE_THREAD = false;