Turn some license strings into lib.licenses values

pkgs/tools/text/xml/html-xml-utils/default.nix

@@ -14,6 +14,6 @@ stdenv.mkDerivation rec {
   meta = {
     description = "Utilities for manipulating HTML and XML files";
     homepage = http://www.w3.org/Tools/HTML-XML-utils/;
-    license = "free-non-copyleft";
+    license = "free-non-copyleft"; #TODO W3C
   };
 }

pkgs/tools/text/xml/rxp/default.nix

@@ -13,7 +13,7 @@ stdenv.mkDerivation {
     cp rxp $out/bin
   '';
   meta = {
-    license = "GPL";
+    license = stdenv.lib.licenses.gpl2Plus;
     description = "a validating XML parser written in C";
     homepage = "http://www.cogsci.ed.ac.uk/~richard/rxp.html";
   };

pkgs/tools/text/xml/xmlstarlet/default.nix

@@ -26,6 +26,6 @@ stdenv.mkDerivation rec {
   meta = {
     description = "A command line tool for manipulating and querying XML data";
     homepage = http://xmlstar.sourceforge.net/;
-    license = "bsd";
+    license = stdenv.lib.licenses.mit;
   };
 }