Fix invalid Qt version check resulting in "What's this" buttons still showing on Win

(cherry picked from commit f976b0d)

Author: nyalldawson

src/app/main.cpp

@@ -842,7 +842,7 @@ int main( int argc, char *argv[] )
   QCoreApplication::setOrganizationDomain( QgsApplication::QGIS_ORGANIZATION_DOMAIN );
   QCoreApplication::setApplicationName( QgsApplication::QGIS_APPLICATION_NAME );
   QCoreApplication::setAttribute( Qt::AA_DontShowIconsInMenus, false );
-#if QT_VERSION >= 0x051000
+#if QT_VERSION >= QT_VERSION_CHECK(5, 10, 0)
   QCoreApplication::setAttribute( Qt::AA_DisableWindowContextHelpButton, true );
 #endif