Don’t show file dialog before calling selectFile()

selectFile() is a no-op if the dialog is visible and
its line edit has focus, which will happen at some
point after show() is called.

In other words this is a race, and the test will pass/fail
depending on the timing of the platform implementation.

Task-number: QTBUG-66536
Change-Id: I03957edb6496d17af7a8ed1d4ca86435375e0d40
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

tests/auto/widgets/dialogs/qfiledialog/tst_qfiledialog.cpp

@@ -933,7 +933,6 @@ void tst_QFiledialog::selectFiles()
     QSignalSpy spyDirectoryEntered(&fd, SIGNAL(directoryEntered(QString)));
     QSignalSpy spyFilesSelected(&fd, SIGNAL(filesSelected(QStringList)));
     QSignalSpy spyFilterSelected(&fd, SIGNAL(filterSelected(QString)));
-    fd.show();
     fd.setFileMode(QFileDialog::ExistingFiles);
 
     QString filesPath = fd.directory().absolutePath();