perf evsel: Actually show symbol offset in stack trace when requested

Symbol offset is one of the fields that can be requested in perf-script.
Currently you do not get that data when requested. e.g.,

perf script -f comm,tid,pid,time,cpu,sym,symoff,ip
...
gcc  6201/6201  [006] 762250.617897:
    ffffffff81090d95 update_curr
    ffffffff810911b8 dequeue_entity
    ffffffff81091825 dequeue_task_fair
    ffffffff81087163 dequeue_task
    ffffffff81087c03 deactivate_task
...

With this patch you get the offset:
...
gcc  6201/6201  [006] 762250.617897:
    ffffffff81090d95 update_curr+0x1c5
    ffffffff810911b8 dequeue_entity+0x28
    ffffffff81091825 dequeue_task_fair+0x45
    ffffffff81087163 dequeue_task+0x93
    ffffffff81087c03 deactivate_task+0x23
...
Signed-off-by: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1375024474-45726-1-git-send-email-dsahern@gmail.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -1519,8 +1519,13 @@ void perf_evsel__print_ip(struct perf_evsel *evsel, union perf_event *event,
 			printf("\t%16" PRIx64, node->ip);
 			if (print_sym) {
 				printf(" ");
+				if (print_symoffset) {
+					al.addr = node->ip;
+					symbol__fprintf_symname_offs(node->sym, &al, stdout);
+				} else
 					symbol__fprintf_symname(node->sym, stdout);
 			}
+
 			if (print_dso) {
 				printf(" (");
 				map__fprintf_dsoname(node->map, stdout);