Examples: Removed unused variable (will be used in docking branch tho, undo when merging!)

examples/imgui_impl_sdl.cpp

@@ -51,9 +51,6 @@
 
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
-#if !SDL_HAS_VULKAN
-static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
-#endif
 
 // Data
 static SDL_Window*  g_Window = NULL;