Add "srcline_from" and "srcline_to" branch sort keys that allow to show
the source lines of a branch.

That makes it much easier to track down where particular branches happen
in the program, for example to examine branch mispredictions, or to
associate it with cycle counts:

  % perf record -b -e cycles:p ./tcall
  % perf report --sort srcline_from,srcline_to,mispredict
  ...
    15.10%  tcall.c:18       tcall.c:10       N
    14.83%  tcall.c:11       tcall.c:5        N
    14.12%  tcall.c:7        tcall.c:12       N
    14.04%  tcall.c:12       tcall.c:5        N
    12.42%  tcall.c:17       tcall.c:18       N
    12.39%  tcall.c:7        tcall.c:13       N
    12.27%  tcall.c:13       tcall.c:17       N
  ...

  % perf report --sort srcline_from,srcline_to,cycles
  ...
    17.12%  tcall.c:18       tcall.c:11       1
    17.01%  tcall.c:12       tcall.c:6        1
    16.98%  tcall.c:11       tcall.c:6        1
    15.91%  tcall.c:17       tcall.c:18       1
     6.38%  tcall.c:7        tcall.c:17       7
     4.80%  tcall.c:7        tcall.c:12       8
     4.21%  tcall.c:7        tcall.c:17       8
     2.67%  tcall.c:7        tcall.c:12       7
     2.62%  tcall.c:7        tcall.c:12       10
     2.10%  tcall.c:7        tcall.c:17       9
     1.58%  tcall.c:7        tcall.c:12       6
     1.44%  tcall.c:7        tcall.c:12       5
     1.38%  tcall.c:7        tcall.c:12       9
     1.06%  tcall.c:7        tcall.c:17       13
     1.05%  tcall.c:7        tcall.c:12       4
     1.01%  tcall.c:7        tcall.c:17       6

Open issues:

- Some kernel symbols get misresolved.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/1463775308-32748-1-git-send-email-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>