LU-2800 autoconf: remove LIBCFS_FUNC_DUMP_TRACE test

LU-2800 autoconf: remove LIBCFS_FUNC_DUMP_TRACE test

dump_trace has been upstream since v2.6.23. The reliable argument was
added in v2.6.25. The other bits were added in v2.6.19.
We can remove the test and dead code.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I3b998f62ce4908adf377acd395725493dd717c3a
Reviewed-on: http://review.whamcloud.com/5403
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>