Make string members of wakeup event struct to be deep copied
This fixes the problem found when running the previously added test.
[ RUN ] DefaultFixture.WakeupEventInfoPreservedForStringLiterals
[ OK ] DefaultFixture.WakeupEventInfoPreservedForStringLiterals (2 ms)
[ RUN ] DefaultFixture.WakeupEventInfoPreservedForDynamicallyAllocatedStrings
[ OK ] DefaultFixture.WakeupEventInfoPreservedForDynamicallyAllocatedStrings (0 ms)
[----------] 2 tests from DefaultFixture (2 ms total)
Change-Id: I24fecd9a78767beda7fafce67f69fae6d53ebf1d