iortcw: fix build

  src = fetchFromGitHub {

    owner = "iortcw";

    repo = "iortcw";

    rev = finalAttrs.version;

    sha256 = "0g5wgqb1gm34pd05dj2i8nj3qhsz0831p3m7bsgxpjcg9c00jpyw";

    tag = finalAttrs.version;

    hash = "sha256-3F8JAEuPydufXqeOGwYCX0M8pEVRyFZAu2TUFxZ+vDw=";

  };

  # Constexpr is a reserved keyword since C++11 that can't be overwritten. Replacing constexpr with

  # const_expr is necessary in this case for the build to function.

  postPatch = ''

    substituteInPlace code/tools/lcc/src/{c.h,init.c,simp.c,stmt.c} \

      --replace-fail 'constexpr' 'const_expr'

  '';

  enableParallelBuilding = true;

  sourceRoot = "${finalAttrs.src.name}/SP";