Add support for "none" QT_IM_MODULE

Do not try to load any input method when QT_IM_MODULE is set to "none".

Change-Id: I695cb76d616bb2ce5021979bae2790b2f286122d
Reviewed-by: Pekka Vuorela <pekka.ta.vuorela@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/platformsupport/inputcontext/qplatforminputcontextfactory_qpa.cpp

@@ -83,8 +83,11 @@ QPlatformInputContext *QPlatformInputContextFactory::create()
     QPlatformInputContext *ic = 0;
 
     QString icString = QString::fromLatin1(qgetenv("QT_IM_MODULE"));
-    ic = create(icString);
 
+    if (icString == QStringLiteral("none"))
+        return 0;
+
+    ic = create(icString);
     if (ic && ic->isValid())
         return ic;