[6/7] windowscodecs: Add some tests for IWICMetadataQueryReader.

[Vincent Povirk]

> +                    if (CompareStringW(LOCALE_NEUTRAL, NORM_IGNORECASE, queryW, len-1, name, len-1) == CSTR_EQUAL && decoder_data[j].query[len - 1] != 0)
> +                    {
> +                        if (winetest_debug > 1)
> +                            trace("query: %s\n", wine_dbgstr_w(queryW + len - 1));
> +                        PropVariantInit(&value);

Shouldn't this be PropVariantClear?