Add a handy tool to collapse threads in pstacks

This commit imports a very useful tool that summarizes/collapses
threads from gdb pstacks. I found it very useful in analyzing
pstacks with large number of threads, specially in Impala's context.

Credit to the original author at https://poormansprofiler.org/
(Slightly modified for better input handling).

Example Usages:
---------------
summarize-pstacks foo.pstack
summarize-pstacks foo_*.pstack
cat foo.pstack | summarize-pstacks
cat foo_*.pstack | summarize-pstacks

Change-Id: I0d00f7cea5fe01ff8b2511f4e04db5d5ad1c82f4
Reviewed-on: http://gerrit.cloudera.org:8080/11926
Reviewed-by: Bharath Vissapragada <bharathv@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>

bin/rat_exclude_files.txt

@@ -141,6 +141,9 @@ tests/shell/test_var_substitution.sql
 # Generated by Apache-licensed software:
 be/src/transport/config.h
 
+# BSD 2-Clause license:
+bin/summarize-pstacks
+
 # BSD 3-clause license that RAT can't seem to identify:
 cmake_modules/FindJNI.cmake
 

bin/summarize-pstacks

@@ -0,0 +1,40 @@
+#!/bin/bash
+#
+# Copyright (c) 2018, Mark Callaghan and Domas Mituzas
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#     * The names of its contributors may not be used to endorse or promote products
+#       derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS BE LIABLE FOR ANY
+# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Credit: https://github.com/mdcallag/mytools/blob/master/scripts/pmp.sh
+
+# Example usage:
+#
+# summarize-pstacks foo.pstack
+# summarize-pstacks foo_*.pstack
+# cat foo.pstack | summarize-pstacks
+# cat foo_*.pstack | summarize-pstacks
+
+awk '
+  BEGIN { s = ""; }
+  /^Thread/ { print s; s = ""; }
+  /^\#/ { if (s != "" ) { s = s "," $4} else { s = $4 } }
+  END { print s }' "${1:-/dev/stdin}" | sort | uniq -c | sort -r -n -k 1,1