valgrind: suppressions file might not be in current directory

test/nginx_system_test.sh

@@ -174,8 +174,9 @@ check_not_simple grep @@ $PAGESPEED_CONF
 
 # start nginx with new config
 if $USE_VALGRIND; then
-  (valgrind -q --leak-check=full --gen-suppressions=all --show-possibly-lost=no \
-      --log-file=$TEST_TMP/valgrind.log --suppressions=valgrind.sup \
+  (valgrind -q --leak-check=full --gen-suppressions=all \
+            --show-possibly-lost=no --log-file=$TEST_TMP/valgrind.log \
+            --suppressions="$this_dir/valgrind.sup" \
       $NGINX_EXECUTABLE -c $PAGESPEED_CONF) & VALGRIND_PID=$!
   trap "echo 'terminating valgrind!' && kill -s sigterm $VALGRIND_PID" EXIT
   echo "Wait until nginx is ready to accept connections"