test: mark test-vm-timeout flaky on windows

PR-URL: nodejs#7359
Refs: nodejs#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

@@ -7,7 +7,8 @@ prefix parallel
 [true] # This section applies to all platforms
 
 [$system==win32]
-test-tick-processor     : PASS,FLAKY
+test-tick-processor : PASS,FLAKY
+test-vm-timeout     : PASS,FLAKY
 
 [$system==linux]
 test-tick-processor           : PASS,FLAKY