relates to:

• SR-141 Complex C header files macros are ignored

Issue Description:

I am integrating libSDL2 with Swift with a modulemap. Many of the simple functions that take simple arguments works, for instance SDL_Init() and SDL_VideoInit().

However, the compiler cannot find SDL_Window or SDL_WINDOWPOS_CENTERED.

SDL_Window is defined as:
typedef struct SDL_Window SDL_Window;

and SDL_WINDOWPOS_CENTERED as:

#define SDL_WINDOWPOS_CENTERED_MASK 0x2FFF0000
#define SDL_WINDOWPOS_CENTERED_DISPLAY(X) (SDL_WINDOWPOS_CENTERED_MASK|(X))
#define SDL_WINDOWPOS_CENTERED SDL_WINDOWPOS_CENTERED_DISPLAY(0)
#define SDL_WINDOWPOS_ISCENTERED(X) \
(((X)&0xFFFF0000) == SDL_WINDOWPOS_CENTERED_MASK)