Fix test when accessing patched plugin too fast

At least one OS (QNX) can't dlopen() a library that is still
open for writing elsewhere

Fixes: QTBUG-101020
Change-Id: I84ca709a65fc824ec4b3e3f1ea03704bf1cc0414
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 81c6f224c4f05db099d4690f2bc36455e1b943b4)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

tests/auto/corelib/plugin/qplugin/tst_qplugin.cpp

@@ -236,6 +236,11 @@ void tst_QPlugin::scanInvalidPlugin()
         memset(data + offset + metadata.size(), 0, 512 - metadata.size());
     }
 
+#if defined(Q_OS_QNX)
+    // On QNX plugin access is still too early
+    QTest::qSleep(1000);
+#endif
+
     // now try to load this
     QFETCH(bool, loads);
     QFETCH(QString, errMsg);