Make sure Pango2 build and run better on Windows (was: Adapt pangowin32 to Pango2)

Hi,

(Please note, this is not meant to cover the work for MR !600 (closed), but to make the Pango DLL buildable on Windows with the newer API layout of Pango-2.x)

Note that this does not yet make the examples and tests to build, as this lacks a HbFontMap implementation for Windows, which MR !600 (closed) covers, and possibly I will look into a GDI/Uniscribe based approach as there is also Cairo that needs to be factored in as Cairo does not yet only has since very recently in the unstable branches a D2D/DirectWrite backend upstream, which is more fit for a separate MR, which is also attempted in this MR since we have GDI interop in DirectWrite.

With blessings, thank you!