Check for symvers.xz support in addition to symvers.gz,
due to unnanounced unilateral change[1][2] in the kernel packaging.
[1] 2644665657
[2] 2db77a072a
* weak-modules (make_kernel_file_names): Interpret all arguments after
the second as a list of suffixes, iterate over them
(find_kernel_file): Switch print and suffix arguments, interpret all
argument after print as suffixes, pass them to make_kernel_file_names.
(find_symvers_file): Update the order of arguments in the
find_kernel_file call, add .xz suffix in addition to .gz.
(find_systemmap_file): Update the order of arguments in the
find_kernel_file call.
Resolves: rhbz#2192895
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>