[Feature Request] making lzma optional

[gulafaran]

with the recent xz CVE would it be possible to make lzma optional aswell in meson options? without knowing much of the source code it is perhaps to tightly integrated? but never hurts to ask.

[hughsie]

Yes, it doesn't give me the soft-and-fuzzies either. Now we also have a libzstd optional dep I think making it optional is a very good idea. Give me a few mins.