qt: port atomic_flag doresize from master

src/include/86box/plat.h

@@ -66,16 +66,17 @@ extern int strnicmp(const char* s1, const char* s2, size_t n);
 
 #ifdef __cplusplus
 #include <atomic>
-#define atomic_flag std::atomic_flag
+#define atomic_flag_t std::atomic_flag
 extern "C" {
 #else
 #include <stdatomic.h>
+#define atomic_flag_t atomic_flag
 #endif
 
 /* Global variables residing in the platform module. */
 extern int	dopause,			/* system is paused */
 		mouse_capture;			/* mouse is captured in app */
-extern atomic_flag doresize;			/* screen resize requested */
+extern atomic_flag_t doresize;			/* screen resize requested */
 extern volatile int	is_quit;				/* system exit requested */
 
 #ifdef MTR_ENABLED

src/qt/qt_main.cpp

@@ -80,12 +80,11 @@ main_thread_fn()
         }
 
         /* If needed, handle a screen resize. */
-        if (doresize && !video_fullscreen && !is_quit) {
+        if (!atomic_flag_test_and_set(&doresize) && !video_fullscreen && !is_quit) {
             if (vid_resize & 2)
                 plat_resize(fixed_size_x, fixed_size_y);
             else
                 plat_resize(scrnsz_x, scrnsz_y);
-            doresize = 0;
         }
     }
 

src/qt/qt_mainwindow.cpp

@@ -1067,7 +1067,7 @@ static void update_scaled_checkboxes(Ui::MainWindow* ui, QAction* selected) {
     reset_screen_size();
     device_force_redraw();
     video_force_resize_set(1);
-    doresize = 1;
+    atomic_flag_clear(&doresize);
     config_save();
 }