xfitter: enable WITH_YAML support on darwin

pkgs/applications/science/physics/xfitter/default.nix

@@ -1,5 +1,6 @@
 { lib, stdenv, fetchurl, apfel, apfelgrid, applgrid, blas, gfortran, lhapdf, lapack, libyaml, lynx
 , mela, root5, qcdnum, which, libtirpc
+, memorymappingHook, memstreamHook
 }:
 
 stdenv.mkDerivation rec {
@@ -36,9 +37,8 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ gfortran which ];
   buildInputs =
-    [ apfel apfelgrid applgrid blas lhapdf lapack mela root5 qcdnum ]
-    # pdf2yaml requires fmemopen and open_memstream which are not readily available on Darwin
-    ++ lib.optional (!stdenv.isDarwin) libyaml
+    [ apfel apfelgrid applgrid blas lhapdf libyaml lapack mela root5 qcdnum ]
+    ++ lib.optionals (stdenv.system == "x86_64-darwin") [ memorymappingHook memstreamHook ]
     ++ lib.optional (stdenv.hostPlatform.libc == "glibc") libtirpc
     ;
   propagatedBuildInputs = [ lynx ];