WinForms: Fix resizing indexed images on windows, which has the same restrictions as on mono
WinForms: Fix resizing indexed images on windows, which has the same restrictions as on mono

bbqchickenrobot/Eto-1,l8s/Eto,PowerOfCode/Eto,bbqchickenrobot/Eto-1,PowerOfCode/Eto,PowerOfCode/Eto,l8s/Eto,l8s/Eto,bbqchickenrobot/Eto-1