ICaptureGraphBuilder::RenderStream needs to enumerate pins, and to
prevent duplication I implemented a bit of findpin first.

gdi32: Add loading and processing of GSUB table vert/vrt2 functions for proper tategaki (vertical writing).

msi: Passing NULL for szBuffer and NULL for pcchValueBuf into MsiGetProductInfo{A, W} shouldn't crash.

Add a test for this.

In JOIN_fetch_int and JOIN_fetch_stream, prev_rows should be multiplied 
by the rows encountered in the current table so that prev_rows contains 
all of counts of the rows encountered multiplied together, rather than 
just the count of the rows in the last table encountered.

Store it in the URL cache entry and allow it to be retrieved by 
RetrieveUrlCacheEntryFile and other functions.