perf lock: Support using -f to override perf.data file ownership

perf lock: Support using -f to override perf.data file ownership

Enable perf lock to use perf.data when it is not owned by current user
or root.

Example:

 # perf lock record ls
 # chown Yunlong.Song:Yunlong.Song perf.data
 # ls -al perf.data
 -rw------- 1 Yunlong.Song Yunlong.Song 4880686 Apr  2 14:14 perf.data
 # id
 uid=0(root) gid=0(root) groups=0(root),64(pkcs11)

Before this patch:

 # perf lock report
 File perf.data not owned by current user or root (use -f to override)
 Initializing perf session failed
 # perf lock report -f
   Error: unknown switch `f'

  usage: perf lock report [<options>]

     -k, --key <acquired>  key for sorting (acquired / contended /
     avg_wait / wait_total / wait_max / wait_min)

As shown above, the -f option does not work at all.

After this patch:

 # perf lock report
 File perf.data not owned by current user or root (use -f to override)
 Initializing perf session failed
 # perf lock report -f
                Name   acquired  contended   avg wait (ns) total wait (ns) ...

 &ldata->output_l...        128          0               0               0 ...
          &ctx->lock        114          0               0               0 ...
         &p->pi_lock        112          0               0               0 ...
 &(&pool->lock)->...        112          0               0               0 ...
 &(&dentry->d_loc...         70          0               0               0 ...
 &(&newf->file_lo...         62          0               0               0 ...
 &(&fs->lock)->rl...         43          0               0               0 ...
 ...

As shown above, the -f option really works now.

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1427982439-27388-6-git-send-email-yunlong.song@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>