Make string members of wakeup event struct to be deep copied

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