perf top: Add missing newline if the 'uid' is invalid

Add missing newline if the 'uid' is invalid:

  hubble:~> perf top --stdio -u help
  Error:
  Invalid User: helphubble:~>

Fixed by this patch:

  comet:~/tip/tools/perf> perf top --stdio -u help
  Error:
  Invalid User: help
  comet:~/tip/tools/perf>

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20131112232609.GA31474@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>