perf lock contention: Track and show siglock with address

Likewise, we can display siglock by following the pointer like
current->sighand->siglock.

  $ sudo ./perf lock con -abl -- sleep 1
   contended   total wait     max wait     avg wait            address   symbol

          16      2.18 ms    305.35 us    136.34 us   ffffffff92e06080   tasklist_lock
          28    521.78 us     31.16 us     18.63 us   ffff8cc703783ec4
           7    119.03 us     23.55 us     17.00 us   ffff8ccb92479440
          15     88.29 us     10.06 us      5.89 us   ffff8cd560b5f380   siglock
           7     37.67 us      9.16 us      5.38 us   ffff8d053daf0c80
           5      8.81 us      4.92 us      1.76 us   ffff8d053d6b0c80

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230313204825.2665483-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>