Windows GDK Support (#5830)

* Added GDK

* Simplfied checks in SDL_config_wingdk.h

* Added testgdk sample

* Added GDK readme

* Fixed error in merge of SDL_windows.h

* Additional GDK fixes

* OpenWatcom should not export _SDL_GDKGetTaskQueue

* Formatting fixes

* Moved initialization code into SDL_GDKRunApp

src/video/SDL_video.c

@@ -1667,7 +1667,7 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
     /* Clear minimized if not on windows, only windows handles it at create rather than FinishWindowCreation,
      * but it's important or window focus will get broken on windows!
      */
-#if !defined(__WIN32__)
+#if !defined(__WIN32__) && !defined(__GDK__)
     if (window->flags & SDL_WINDOW_MINIMIZED) {
         window->flags &= ~SDL_WINDOW_MINIMIZED;
     }
@@ -2534,7 +2534,7 @@ SDL_CreateWindowFramebuffer(SDL_Window * window)
             attempt_texture_framebuffer = SDL_FALSE;
         }
 
-        #if defined(__WIN32__) /* GDI BitBlt() is way faster than Direct3D dynamic textures right now. (!!! FIXME: is this still true?) */
+        #if defined(__WIN32__) || defined(__WINGDK__) /* GDI BitBlt() is way faster than Direct3D dynamic textures right now. (!!! FIXME: is this still true?) */
         else if ((_this->CreateWindowFramebuffer != NULL) && (SDL_strcmp(_this->name, "windows") == 0)) {
             attempt_texture_framebuffer = SDL_FALSE;
         }

src/video/windows/SDL_windowsevents.c

@@ -53,6 +53,10 @@
 #include "wmmsg.h"
 #endif
 
+#ifdef __GDK__
+#include "../../core/gdk/SDL_gdk.h"
+#endif
+
 /* #define HIGHDPI_DEBUG */
 
 /* Masks for processing the windows KEYDOWN and KEYUP messages */
@@ -1803,6 +1807,10 @@ WIN_PumpEvents(_THIS)
 
     /* Update mouse capture */
     WIN_UpdateMouseCapture();
+
+#ifdef __GDK__
+    GDK_DispatchTaskQueue();
+#endif
 }