LU-13676 tools: find unique stacks from sysrq-t

LU-13676 tools: find unique stacks from sysrq-t

Enhance the crash-find-unique-traces.awk script to be more useful:
- allow parsing output from sysrq-t
- skip leading fields from input (e.g. timestamps, syslog header)
- sort messages to avoid duplicates
- handle some variance in kernel function names
- print thread names as well as PIDs for all matching threads
- print number of threads matching a particular stack trace
- warn if parts of the stack traces were lost due to buffer overflow

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Icfd70fbf255f413ca1aab0b94c62754e4c00628d
Reviewed-on: https://review.whamcloud.com/40956
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>