Qt: fix random QWinTaskbarProgress crashes

rpcs3/rpcs3qt/gs_frame.cpp

@@ -7,6 +7,7 @@
 #include "Emu/System.h"
 #include "Emu/Cell/Modules/cellScreenshot.h"
 
+#include <QCoreApplication>
 #include <QKeyEvent>
 #include <QMessageBox>
 #include <string>
@@ -84,7 +85,8 @@ gs_frame::gs_frame(const QRect& geometry, const QIcon& appIcon, const std::share
 gs_frame::~gs_frame()
 {
 #ifdef _WIN32
-	if (m_tb_progress)
+	// QWinTaskbarProgress::hide() will crash if the application is already about to close, even if the object is not null.
+	if (m_tb_progress && !QCoreApplication::closingDown())
 	{
 		m_tb_progress->hide();
 	}

rpcs3/rpcs3qt/msg_dialog_frame.cpp

@@ -1,6 +1,7 @@
 #include "msg_dialog_frame.h"
 #include "custom_dialog.h"
 
+#include <QCoreApplication>
 #include <QPushButton>
 #include <QFormLayout>
 
@@ -173,7 +174,8 @@ msg_dialog_frame::msg_dialog_frame() {}
 msg_dialog_frame::~msg_dialog_frame()
 {
 #ifdef _WIN32
-	if (m_tb_progress)
+	// QWinTaskbarProgress::hide() will crash if the application is already about to close, even if the object is not null.
+	if (m_tb_progress && !QCoreApplication::closingDown())
 	{
 		m_tb_progress->hide();
 	}

rpcs3/rpcs3qt/progress_dialog.cpp

@@ -1,5 +1,6 @@
 #include "progress_dialog.h"
 
+#include <QCoreApplication>
 #include <QLabel>
 
 #ifdef _WIN32
@@ -37,7 +38,11 @@ progress_dialog::progress_dialog(const QString &windowTitle, const QString &labe
 progress_dialog::~progress_dialog()
 {
 #ifdef _WIN32
+	// QWinTaskbarProgress::hide() will crash if the application is already about to close, even if the object is not null.
+	if (!QCoreApplication::closingDown())
+	{
 		m_tb_progress->hide();
+	}
 #elif HAVE_QTDBUS
 	UpdateProgress(0);
 #endif