[Bug 36594] valgrind shows uninitialized memory use in windowscodecs/tests/metadata.c

http://bugs.winehq.org/show_bug.cgi?id=36594

--- Comment #2 from Vincent Povirk  ---
The PNG one is a case where a winapi function is supposed to initialize the
value, but that function isn't implemented yet. We should have the test either
initialize it first, or only check if the function succeeds.

But I don't care much myself because we should just implement the function.