licenses: add HPND-sell-variant

lib/licenses.nix

···
     fullName = "Historic Permission Notice and Disclaimer";
   };
 
+  hpndSellVariant = spdx {
+    fullName = "Historical Permission Notice and Disclaimer - sell variant";
+    spdxId = "HPND-sell-variant";
+  };
+
   # Intel's license, seems free
   iasl = {
     fullName = "iASL";