python3Packages.lightgbm: fix for darwin

package appears to have its own openmp library detection now and doesn't
need the hacks. also add pythonImportsCheck.

pkgs/development/python-modules/lightgbm/default.nix

@@ -23,19 +23,7 @@ buildPythonPackage rec {
 
   dontUseCmakeConfigure = true;
 
-  # we never actually explicitly call the install command so this is the only way
-  # to inject these options to it - however, openmp-library doesn't appear to have
-  # any effect, so we have to inject it into NIX_LDFLAGS manually below
-  postPatch = lib.optionalString stdenv.cc.isClang ''
-    cat >> setup.cfg <<EOF
-
-    [install]
-    openmp-include-dir=${llvmPackages.openmp}/include
-    openmp-library=${llvmPackages.openmp}/lib/libomp.dylib
-
-    EOF
-  '';
-
+  buildInputs = lib.optional stdenv.cc.isClang [ llvmPackages.openmp ];
   propagatedBuildInputs = [
     numpy
     scipy
@@ -44,14 +32,13 @@ buildPythonPackage rec {
 
   postConfigure = ''
     export HOME=$(mktemp -d)
-  '' + lib.optionalString stdenv.cc.isClang ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -L${llvmPackages.openmp}/lib -lomp"
   '';
 
   # The pypi package doesn't distribute the tests from the GitHub
   # repository. It contains c++ tests which don't seem to wired up to
   # `make check`.
   doCheck = false;
+  pythonImportsCheck = [ "lightgbm" ];
 
   meta = with lib; {
     description = "A fast, distributed, high performance gradient boosting (GBDT, GBRT, GBM or MART) framework";