Use atomic_bool instead of atomic_flag for doresizes

atomic_flag seems to be broken on Windows for clearing them outside the
thread they were tested and set in

src/qt/qt_main.cpp

@@ -291,11 +291,12 @@ int main(int argc, char* argv[]) {
         /* If needed, handle a screen resize. */
         for (int i = 0; i < MONITORS_NUM; i++) {
             if (!monitors[i].target_buffer) continue;
-            if (!atomic_flag_test_and_set(&doresize_monitors[i]) && !video_fullscreen && !is_quit) {
+            if (atomic_load(&doresize_monitors[i]) == 1 && !video_fullscreen && !is_quit) {
                 if (vid_resize & 2)
                     plat_resize_monitor(fixed_size_x, fixed_size_y, i);
                 else
                     plat_resize_monitor(monitors[i].mon_scrnsz_x, monitors[i].mon_scrnsz_y, i);
+                atomic_store(&doresize_monitors[i], 0);
             }
         }
 

src/qt/qt_mainwindow.cpp

@@ -1875,6 +1875,9 @@ void MainWindow::on_actionHiDPI_scaling_triggered()
     dpi_scale ^= 1;
     ui->actionHiDPI_scaling->setChecked(dpi_scale);
     emit resizeContents(monitors[0].mon_scrnsz_x, monitors[0].mon_scrnsz_y);
+    for (int i = 1; i < MONITORS_NUM; i++) {
+        if (renderers[i]) emit resizeContentsMonitor(monitors[i].mon_scrnsz_x, monitors[i].mon_scrnsz_y, i);
+    }
 }
 
 void MainWindow::on_actionHide_status_bar_triggered()

src/qt/qt_rendererstack.cpp

@@ -44,6 +44,7 @@
 #endif
 
 extern "C" {
+#include <86box/86box.h>
 #include <86box/mouse.h>
 #include <86box/plat.h>
 #include <86box/video.h>
@@ -446,6 +447,7 @@ RendererStack::blitCommon(int x, int y, int w, int h)
 
 void RendererStack::closeEvent(QCloseEvent* event)
 {
+    if (cpu_thread_run == 0 || is_quit == 0) { event->accept(); return; }
     event->ignore();
     main_window->close();
 }