perf annotate: Support event group view for --print-line

Dynamically allocate source_line_percent according to a number of group
members and save nr_pcnt to the struct source_line.  This way we can
handle multiple events in a general manner.

However since the size of struct source_line is not fixed anymore,
iterating whole source_line should care about its size.

  $ perf annotate --group --stdio --print-line

  Sorted summary for file /lib/ld-2.11.1.so
  ----------------------------------------------
     33.33    0.00 /build/buildd/eglibc-2.11.1/elf/rtld.c:381
     33.33    0.00 /build/buildd/eglibc-2.11.1/elf/dynamic-link.h:128
     33.33    0.00 /build/buildd/eglibc-2.11.1/elf/do-rel.h:105
      0.00   75.00 /build/buildd/eglibc-2.11.1/elf/dynamic-link.h:137
      0.00   25.00 /build/buildd/eglibc-2.11.1/elf/dynamic-link.h:187
  ...

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1362462812-30885-9-git-send-email-namhyung@kernel.org


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