If we don't use .ordering_requires_timestamps we'll end up trying to order
events with no timestamps when running on older kernels.

Problem introduced in eac23d1c.

After the last three fixes, perf scripting is back working, tested with
new perf userspace on old and new (with sample_id_all) kernels.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ian Munsie <imunsie@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Torok Edwin <edwintorok@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>