Add necessary cflags and cflags_cc for winrt compilation.
Add 'dawn_is_winuwp'.
Set 'dawn_enable_vulkan' and 'dawn_supports_glfw_for_windowing' when compiling for UWP.
Link d3d12, d3d11 and dxgi stub libs when compiling for UWP.
Use LoadPackagedLibrary instead of LoadLibraryA in DynamicLib when compiling for UWP.
Swapchain related changes will be in another commit.
Bug: dawn:766
Change-Id: I1210798a21cc175bab77281403d262d4bfb02d99
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/48480
Commit-Queue: 陈俊嘉 <cjj19970505@live.cn>
Reviewed-by: Rafael Cintron <rafael.cintron@microsoft.com>
windows.h adds macros such as `#define GetMessage GetMessageA` which
cause conflicts in naming when for example a class definition is before
windows.h and a use is after windows.h
Add a header that can be used both to include windows.h and remove
defines, and to only remove defines (when windows.h is included by)
external dependencies.
