hpx: add hwloc to propagatedBuildInputs

hpx will only compile programs if hwloc is availible.
Any package that uses hpx will also need hwloc to be availible.

Without this change CMake will complain HWLoc is not availible.

see: https://hpx-docs.stellar-group.org/branches/release/html/quickstart.html#hpx-dependencies

pkgs/development/libraries/hpx/default.nix

···
-{ lib, stdenv, fetchFromGitHub, asio, boost, cmake, hwloc, gperftools, ninja
-, pkg-config, python3 }:
+{ lib
+, stdenv
+, fetchFromGitHub
+, asio
+, boost
+, cmake
+, hwloc
+, gperftools
+, ninja
+, pkg-config
+, python3
+}:
 
 stdenv.mkDerivation rec {
   pname = "hpx";
···
     hash = "sha256-1gLDwgCqv+3+rOSG7a3fFsnjqfKpnPpWnBmrW+z+jWw=";
   };
 
-  buildInputs = [ asio boost hwloc gperftools ];
+  propagatedBuildInputs = [ hwloc ];
+  buildInputs = [ asio boost gperftools ];
   nativeBuildInputs = [ cmake pkg-config python3 ];
 
   strictDeps = true;