The samples are offered under is GPL2. GPL2 is a source license.
You can do whatever you want with derivative works, just don't relicense anything from lmms samples library as your own!
Any and All relicensing is illegal!
Note, bundled project files aren't C00 cleared either. If you have a question about a particular track, let a developer know and we'll do our best to get you in contact with the original artist.