perf tools: Handle the case with and without the "signed" trace field

The trace format files now have a "signed" field. But we should
still be able to handle the kernels that do not have this field.

Signed-off-by: Steven Rostedt <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
1 file changed