trace2 tests: fix PTHREADS prereq

The prereq guard added in 14903c8 (trace2 tests: guard pthread test
with "PTHREAD", 2022-11-24) lacks the S in PTHREADS, causing it to never
be satisfied.  Fix the spelling of the prereq.

Signed-off-by: Todd Zullinger <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: tmzullinger

t/t0211-trace2-perf.sh

@@ -203,7 +203,7 @@ test_expect_success 'stopwatch timer test/test1' '
 	have_timer_event "main" "timer" "test" "test1" 5 actual
 '
 
-test_expect_success PTHREAD 'stopwatch timer test/test2' '
+test_expect_success PTHREADS 'stopwatch timer test/test2' '
 	test_when_finished "rm trace.perf actual" &&
 	test_config_global trace2.perfBrief 1 &&
 	test_config_global trace2.perfTarget "$(pwd)/trace.perf" &&
@@ -249,7 +249,7 @@ test_expect_success 'global counter test/test1' '
 	have_counter_event "main" "counter" "test" "test1" 15 actual
 '
 
-test_expect_success PTHREAD 'global counter test/test2' '
+test_expect_success PTHREADS 'global counter test/test2' '
 	test_when_finished "rm trace.perf actual" &&
 	test_config_global trace2.perfBrief 1 &&
 	test_config_global trace2.perfTarget "$(pwd)/trace.perf" &&