perf srcline: Show correct function name for srcline of callchains

When libbfd is not used, it doesn't show proper function name and reuse
the original symbol of the sample.  That's because it passes the
original sym to inline_list__append().  As `addr2line -f` returns
function names as well, use that to create an inline_sym and pass it to
inline_list__append().

For example, following data shows that inlined entries of main have same
name (main).

Before:
  $ perf report -g srcline -q | head
      45.22%  inlining     libm-2.26.so      [.] __hypot_finite
              |
              ---__hypot_finite ??:0
                 |
                 |--44.15%--hypot ??:0
                 |          main complex:589
                 |          main complex:597
                 |          main complex:654
                 |          main complex:664
                 |          main inlining.cpp:14

After:
  $ perf report -g srcline -q | head
      45.22%  inlining     libm-2.26.so      [.] __hypot_finite
              |
              ---__hypot_finite
                 |
                 |--44.15%--hypot
                 |          std::__complex_abs complex:589 (inlined)
                 |          std::abs<double> complex:597 (inlined)
                 |          std::_Norm_helper<true>::_S_do_it<double> complex:654 (inlined)
                 |          std::norm<double> complex:664 (inlined)
                 |          main inlining.cpp:14

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20171031020654.31163-2-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>