perf intel-pt: Fix sync_switch INTEL_PT_SS_NOT_TRACING

sync_switch is a facility to synchronize decoding more closely with the
point in the kernel when the context actually switched.

In one case, INTEL_PT_SS_NOT_TRACING state was not correctly
transitioning to INTEL_PT_SS_TRACING state due to a missing case clause.
Add it.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1527762225-26024-2-git-send-email-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/intel-pt.c

@@ -1521,6 +1521,7 @@ static int intel_pt_sample(struct intel_pt_queue *ptq)
 
 	if (intel_pt_is_switch_ip(ptq, state->to_ip)) {
 		switch (ptq->switch_state) {
+		case INTEL_PT_SS_NOT_TRACING:
 		case INTEL_PT_SS_UNKNOWN:
 		case INTEL_PT_SS_EXPECTING_SWITCH_IP:
 			err = intel_pt_next_tid(pt, ptq);