tools/xz: update to 5.4.4

tools/xz: update to 5.4.4

* liblzma and xzdec can now build against WASI SDK when threading
  support is disabled. xz and tests don't build yet.

* CMake:

    - Fixed a bug preventing other projects from including liblzma
      multiple times using find_package().

    - Don't create broken symlinks in Cygwin and MSYS2 unless
      supported by the environment. This prevented building for the
      default MSYS2 environment. The problem was introduced in
      xz 5.4.0.

* Documentation:

    - Small improvements to man pages.

    - Small improvements and typo fixes for liblzma API
      documentation.

* Tests:

    - Added a new section to INSTALL to describe basic test usage
      and address recent questions about building the tests when
      cross compiling.

    - Small fixes and improvements to the tests.

* Translations:

    - Fixed a mistake that caused one of the error messages to not
      be translated. This only affected versions 5.4.2 and 5.4.3.

    - Updated the Chinese (simplified), Croatian, Esperanto, German,
      Korean, Polish, Romanian, Spanish, Swedish, Ukrainian, and
      Vietnamese translations.

    - Updated the German, Korean, Romanian, and Ukrainian man page
      translations.

Signed-off-by: Rosen Penev <rosenp@gmail.com>