[PATCH 2/6] gdiplus: Add helper for saving path objects in metafile

[Vincent Povirk]

We will also eventually need to store region objects in metafiles. The
way paths are stored in metafile regions looks identical to
GetRegionData.

AFAICT the metafile format for regions is the same as GetRegionData,
except that GetRegionData has additional headers.

I think that ideally we should be sharing code for serializing these
object types. I don't think that going through the GdipGetRegionData
API is necessarily the way to do it though.