[thirdparty] upgrade libunwind to 1.6.2

Change-Id: I1698c4a9ff1f07c640f0fcaf35d53e36b5f3c33f
Reviewed-on: http://gerrit.cloudera.org:8080/19853
Tested-by: Kudu Jenkins
Reviewed-by: Yingchun Lai <laiyingchun@apache.org>
1 file changed