[Gotham] Windows build fixes for WMC

See commit messages for the details.

@opdenkamp: you probably want to update https://github.com/xbmc/xbmc/pull/3806 also before merging to xbmc/master

Updated on 02-01-2014:
Rebased and removed the VNSI build fixes since @FernetMenta in the meantime committed a similar fix in 63d52ae716dd6daed2642061d500948bdad7cdd3