test: mark test-vm-timeout flaky on windows

PR-URL: https://github.com/nodejs/node/pull/7359
Refs: https://github.com/nodejs/node/issues/6727
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Joao Reis <reis@janeasystems.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

test/parallel/parallel.status

@@ -8,6 +8,7 @@ prefix parallel
 
 [$system==win32]
 test-tick-processor : PASS,FLAKY
+test-vm-timeout     : PASS,FLAKY
 
 [$system==linux]
 test-tick-processor     : PASS,FLAKY