perf tools: Suggest using -f to override perf.data file ownership message

perf tools: Suggest using -f to override perf.data file ownership message

  # id
  uid=0(root) gid=0(root) groups=0(root)
  # ls -la perf.data
  -rw-------. 1 acme acme 20720 Jul  8 11:35 perf.data

Previously:

  # perf report
  file perf.data not owned by current user or root

Now:

  # perf report
  File perf.data not owned by current user or root (use -f to override)

Suggested-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-0j2wuuegnhv3gljbil8ld6kx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>