[PATCH] Adding LZMA as dep for XML2 on 2.8.0 or higher

[Renato Golin]

  Hi Eric,

  Thanks for the review. There is a catch that I only saw when I installed on a new system: you need libzma-dev installed to build natively, as opposed to before, when you didn't. This is because we link objects statically, so we need the .a, not the .so, which comes bundled with libxml2.

  But since it's not needed for native compilation, there's no point in requiring liblzma-dev for all compilations, and there's no way CMake will lookup native libraries for the architecture you're targeting, so a less intrusive change would be to *only* add the dependency when cross-compiling and explicitly *not* check for it's existence.

  A huge comment on that part of the CMake must exist, so that people understand why it's there that way, of course, unless you know of a better way to do that.

  PS: Sorry for only testing it on a new system now, I should have done that earlier... :(

http://llvm-reviews.chandlerc.com/D1604