perf tests: Implement Zstd comp/decomp integration test

Introduce a basic integration test for Zstd based record
compression/decompression using 'perf record' and 'perf report'.

Committer notes:

Reduce a bit the freq (from 25 kHz to 5 kHz) and the number of /dev/null
records read (from 1000 to 500), reducing the time it takes to something
more in line with the time existing 'perf test' entries take to run.

With that in place:

  $ time perf test zstd
  68: Zstd perf.data compression/decompression              : Ok

  real	0m10.376s
  user	0m0.105s
  sys	0m0.440s
  $ grep "model name" /proc/cpuinfo  | head -1
  model name	: Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
  $
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/dc007ae4-104a-2b7c-316e-275929025f0d@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/record+zstd_comp_decomp.sh

+#!/bin/sh
+# Zstd perf.data compression/decompression
+
+trace_file=$(mktemp /tmp/perf.data.XXX)
+perf_tool=perf
+output=/dev/null
+
+skip_if_no_z_record() {
+	$perf_tool record -h 2>&1 | grep '\-z, \-\-compression\-level'
+}
+
+collect_z_record() {
+	echo "Collecting compressed record file:"
+	$perf_tool record -o $trace_file -g -z -F 5000 -- \
+		dd count=500 if=/dev/random of=/dev/null > $output 2>&1
+}
+
+check_compressed_stats() {
+	echo "Checking compressed events stats:"
+	$perf_tool report -i $trace_file --header --stats | \
+		grep -E "(# compressed : Zstd,)|(COMPRESSED events:)" > $output 2>&1
+}
+
+check_compressed_output() {
+	$perf_tool inject -i $trace_file -o $trace_file.decomp &&
+	$perf_tool report -i $trace_file --stdio | head -n -3 > $trace_file.comp.output &&
+	$perf_tool report -i $trace_file.decomp --stdio | head -n -3 > $trace_file.decomp.output &&
+	diff $trace_file.comp.output $trace_file.decomp.output > $output 2>&1
+}
+
+skip_if_no_z_record || exit 2
+collect_z_record && check_compressed_stats && check_compressed_output
+err=$?
+rm -f $trace_file*
+exit $err