Our time(1) doesn't support -a and -o options.

Index: tests/benchmark/common.sh
--- tests/benchmark/common.sh.orig
+++ tests/benchmark/common.sh
@@ -22,8 +22,6 @@ xseq() {
 # Set TEST_TIME_BIN
 if [ -x "$URCU_TEST_TIME_BIN" ]; then
 	TEST_TIME_BIN="$URCU_TEST_TIME_BIN"
-elif [ -x "/usr/bin/time" ]; then
-	TEST_TIME_BIN="/usr/bin/time"
 else
 	TEST_TIME_BIN=""
 fi
