cmake HAVE_SDL_VULKAN_H examples

Warzone2100/warzone2100 lib/sdl/CMakeLists.txt :127 

CHECK_INCLUDE_FILE_CXX("SDL_vulkan.h" HAVE_SDL_VULKAN_H)

Warzone2100/warzone2100 lib/sdl/CMakeLists.txt :140 

target_compile_definitions(sdl-backend PRIVATE "-DHAVE_SDL_VULKAN_H")