[13/17] windowscodecs: Use PropVariantCompareEx to compare metadata items.

[Vincent Povirk]

This breaks the windowscodecs/metadata test here.

fixme:propsys:PropVariantCompareEx vartype 30 not handled
metadata.c:382: Test failed: GetValue failed, hr=88982f40
fixme:propsys:PropVariantCompareEx vartype 30 not handled
metadata.c:388: Test failed: GetValue failed, hr=88982f40
metadata.c:389: Test failed: unexpected vt: 30
wine: Unhandled page fault on read access to 0x00000000 at address
0x7ed13c05 (thread 0009), starting debugger...