test: avoid memory leak for test_output

PR-URL: https://github.com/libuv/libuv/pull/2017
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: John Barboza <jbarboza@ca.ibm.com>

test/test-spawn.c

@@ -1172,6 +1172,7 @@ TEST_IMPL(argument_escaping) {
   for (i = 0; i < count; ++i) {
     free(test_output[i]);
   }
+  free(test_output);
 
   result = make_program_args(verbatim, 1, &verbatim_output);
   ASSERT(result == 0);