opendht: move to pkgs/development/libraries

location is more appropriate

pkgs/top-level/all-packages.nix

···
 
   opendbx = callPackage ../development/libraries/opendbx { };
 
-  opendht = callPackage ../tools/security/opendht {};
+  opendht = callPackage ../development/libraries/opendht {};
 
   opendkim = callPackage ../development/libraries/opendkim { };