Newest libunwind does support ARM64, and perf is able to utilize it
also.

This patch enables the perf test dwarf unwind for arm64.

 Test result:
  # ./perf test unwind
  25: Test dwarf unwind                                      : Ok
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1427461681-72971-1-git-send-email-wangnan0@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>