Add retry to flaky UnixFileTests.

There is always going to be a race between the two system calls so the workaround to only fail the test if it does not succeed after multiple retries.

Fixes: 145338739

Test: tested with
'CtsLibcoreTestCases:org.apache.harmony.luni.tests.java.io.UnixFileTest
--rerun-until-failure 1000', however the same command didn't repro the
bug on master, hence flaky fix is not confirmed.

Change-Id: I60aa0f7bd31affef8ba9d3c340ca581d425c4d70
1 file changed