perf addr2line: Add a libdw implementation

perf addr2line: Add a libdw implementation

Add an implementation of addr2line that uses libdw.

Other addr2line implementations are slow, particularly in the case of
forking addr2line.

Add an implementation that caches the libdw information in the dso and
uses it to find the file and line number information.

Inline information is supported but because cu_walk_functions_at visits
the leaf function last add a inline_list__append_tail to reverse the
lists order.

Committer testing:

  # perf probe -x ~/bin/perf libdw__addr2line
  Added new event:
    probe_perf:libdw_addr2line (on libdw__addr2line in /home/acme/bin/perf)

  You can now use it in all perf tools, such as:

  	perf record -e probe_perf:libdw_addr2line -aR sleep 1

  #
  # perf stat -e probe_perf:libdw_addr2line perf report -f --dso perf --stdio -s srcfile,srcline
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 4K of event 'cpu/cycles/Pu'
  # Event count (approx.): 5535180842
  #
  # Overhead  Source File   Source:Line
  # ........  ............  ...............
  #
      99.04%  inlineloop.c  inlineloop.c:21
       0.46%  inlineloop.c  inlineloop.c:20

  #
  # (Tip: For tracepoint events, try: perf report -s trace_fields)
  #

   Performance counter stats for 'perf report -f --dso perf --stdio -s srcfile,srcline':

                  44      probe_perf:libdw_addr2line

         0.037260744 seconds time elapsed

         0.025299000 seconds user
         0.011918000 seconds sys
  #

Adding probes to the other addr2line implementations (llvm__addr2line,
libbfd__addr2line and cmd__addr2line) I noticed some fallbacks to the
llvm one:

 Performance counter stats for 'perf report -f --dso perf --stdio -s srcfile,srcline':

                44      probe_perf:libdw_addr2line
                23      probe_perf:llvm_addr2line
                 0	probe_perf:libbfd_addr2line
                 0      probe_perf:cmd_addr2line

Something to investigate further, but at least we don't fallback to the
cmd based one :-)

Reviewed-by: James Clark <james.clark@linaro.org>
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: Howard Chu <howardchu95@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Tony Jones <tonyj@suse.de>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>