Remove rsvg-install.props's during re-generation
Remove rsvg-install.props's during re-generation

This is to ensure the changes in the generated
build/win32/vs10/rsvg-install.props are applied in
build/win32/vs[11|12|14] as well.

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg