WaitForDuration (new test added recently by JDK-8336479) starts a child process to sleep for a long duration. The child process remains behind after the test run has completed, which is problematic on Windows as the make command waits for the process to terminate.

Since JDK-8336479 has integrated, the execution time of jdk:tier1_part1 has gone from ~12m to 1h6m on Windows. It's important to fix this test soon. I attach an initial patch that will kill the child process after testing waitFor.