test_time: Provide a timeout when waiting.

The test_timezone_watch unit test is written to expect a
condition to be signaled when the inotify daemon thread runs.
There exists a small window where the test_timezone_watch
thread can signal the inotify daemon thread while it is not
reading on the underlying file descriptor. If this occurs
the test_timezone_watch thread will wait indefinitely for a
signal that will never arrive.

This change adds a timeout to the condition so it will return
regardless after a period of time.

Change-Id: Ifed981879df6de3d93acd3ee0a70f92546517390