headers: Add enum operators in d2d1.h

This fixes compiler error as following.

JUCE/modules/juce_graphics/native/juce_Direct2DResources_windows.cpp:56:81:
error: assigning to 'D2D1_PRESENT_OPTIONS' from incompatible type 'unsigned int'
56 |         hwndRenderTargetProps.presentOptions = D2D1_PRESENT_OPTIONS_IMMEDIATELY | D2D1_PRESENT_OPTIONS_RETAIN_CONTENTS;
   |                                                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Biswapriyo Nath <nathbappai@gmail.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>