perf test script: Add perl script testing support

perf test script: Add perl script testing support

Basic coverage of perl script support from `perf script`. This is
disabled by default and so the test will most normally skip.

Committer testing:

  $ perf test 'perf script perl'
  106: perf script perl tests                                          : Skip
  $ perf test -vv 'perf script perl'
  106: perf script perl tests:
  --- start ---
  test child forked, pid 578323
  perf script perl test [Skipped: no libperl support]
  ---- end(-2) ----
  106: perf script perl tests                                          : Skip
  $ perf check feature libperl
                 libperl: [ OFF ]  # HAVE_LIBPERL_SUPPORT ( tip: Deprecated, use LIBPERL=1 and install perl-ExtUtils-Embed/libperl-dev to build with it )
  $

Install perl-ExtUtils-Embed, build with LIBPERL=1, rebuild:

  $ perf check feature libperl
                 libperl: [ on  ]  # HAVE_LIBPERL_SUPPORT
  $ perf test 'perf script perl'
  106: perf script perl tests                                          : Ok
  $ perf test -vv 'perf script perl'
  106: perf script perl tests:
  --- start ---
  test child forked, pid 588206
  Testing event: sched:sched_switch
  perf script perl test [Skipped: failed to record sched:sched_switch]
  Testing event: task-clock
  Generating perl script...
  generated Perl script: /tmp/__perf_test_script.RpMn5.pl
  Executing perl script...
  perf script perl test [Success: task-clock triggered $VAR1]
  ---- end(0) ----
  106: perf script perl tests                                          : Ok
  $

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>