torture: Adjust rcuperf trace processing to allow for workqueues

The rcuperf event-trace processing assumes that expedited grace periods
start and end on the same task, an assumption that was violated by moving
expedited grace-period processing to workqueues.  This commit removes
this now-fallacious assumption from rcuperf's event-trace processing.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh

@@ -39,7 +39,7 @@ sed -e 's/us : / : /' |
 tr -d '\015' |
 awk '
 $8 == "start" {
-	if (starttask != "")
+	if (startseq != "")
 		nlost++;
 	starttask = $1;
 	starttime = $3;
@@ -47,17 +47,17 @@ $8 == "start" {
 }
 
 $8 == "end" {
-	if (starttask == $1 && startseq == $7) {
+	if (startseq == $7) {
 		curgpdur = $3 - starttime;
 		gptimes[++n] = curgpdur;
 		gptaskcnt[starttask]++;
 		sum += curgpdur;
 		if (curgpdur > 1000)
 			print "Long GP " starttime "us to " $3 "us (" curgpdur "us)";
-		starttask = "";
+		startseq = "";
 	} else {
 		# Lost a message or some such, reset.
-		starttask = "";
+		startseq = "";
 		nlost++;
 	}
 }