Fix off by one error in valgrind_test.sh

Test Plan: make valgrind_check

Reviewers: sheki

Reviewed By: sheki

Differential Revision: https://reviews.facebook.net/D10185

valgrind_test.sh

@@ -5,7 +5,7 @@
 VALGRIND_DIR=VALGRIND_LOGS
 make -j$(nproc) valgrind_check
 NUM_FAILED_TESTS=$((`wc -l $VALGRIND_DIR/valgrind_failed_tests | awk '{print $1}'` - 1))
-if [ $NUM_FAILED_TESTS -le 1 ]; then
+if [ $NUM_FAILED_TESTS -lt 1 ]; then
   echo No tests have valgrind errors
   exit 0
 else