package/mender: bump to version 2.0.0

In addition:
  - Update hashes for license files due to copyright year change.
  - Add hash for vendor/golang.org/x/text/LICENSE
  - Add hash for vendor/github.com/mendersoftware/go-liblzma/LICENSE
  - Add new dependency xz, as mender now depends on LZMA.

Signed-off-by: Adam Duskett <Aduskett@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>