perf session: Add missing sample flush for piped events

perf session: Add missing sample flush for piped events

Piped events can be sorted so a final flush is needed.

Add that and remove a redundant 'err = 0'.

Signed-off-by: Adrian Hunter <[email protected]>
Reviewed-by: Jiri Olsa <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>