Increase sleep time in the main thread of test 067-preemptive-unpark.

Give a bit more time to the ParkTester thread to honor the
park command.

Test: art/test/testrunner/testrunner.py -t 067-preemptive-unpark
Bug: 22242462
Change-Id: Iba33030e7537cb7cf3751bffc376a9509067b4c6
1 file changed