LU-8560 libcfs: handle stacktrace function address() change

LU-8560 libcfs: handle stacktrace function address() change

Starting in linux kernel 4.6 the address() function
from struct stacktrace now return an int. Update
Lustre to handle this change.

Change-Id: I7d14c9134de3ae5642e2cad7d1d3829eb4ee9c50
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/22207
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>