chore(CI): add portable mode to qmake build

Resolve https://github.com/BLumia/pineapple-pictures/issues/148

This change is sponsored by @EdgarHartel.

app/main.cpp

@@ -52,8 +52,13 @@ int main(int argc, char *argv[])
     parser.process(a);
 
     if (parser.isSet(supportedImageFormats)) {
+#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
         fputs(qPrintable(MainWindow::supportedImageFormats().join(QChar('\n'))), stdout);
         ::exit(EXIT_SUCCESS);
+#else
+        QCommandLineParser::showMessageAndExit(QCommandLineParser::MessageType::Information,
+                                               MainWindow::supportedImageFormats().join(QChar('\n')));
+#endif
     }
 
     MainWindow w;

pineapple-pictures.pro

@@ -9,6 +9,10 @@ TARGET = ppic
 TEMPLATE = app
 DEFINES += PPIC_VERSION_STRING=\\\"x.y.z\\\"
 
+win32 {
+    DEFINES += FLAG_PORTABLE_MODE_SUPPORT=1
+}
+
 # The following define makes your compiler emit warnings if you use
 # any feature of Qt which has been marked as deprecated (the exact warnings
 # depend on your compiler). Please consult the documentation of the