Remove env var to enable accessibility on linux.

Usually we don't have a plugin for this on linux anyway.
But if we do, we should actually allow it to interface with the
system.
When using AT-SPI the plugin can detect if it should be active.
Other plugins can fall back to using an env var if really needed.

Change-Id: Ic9dcfa305e7cdafbf4a93bcc2dc9a0fcd9b9a7a2
Reviewed-by: Jan-Arve Sæther <jan-arve.saether@nokia.com>

src/gui/accessible/qplatformaccessibility_qpa.cpp

@@ -123,10 +123,7 @@ void QPlatformAccessibility::initialize()
     if (isInit)
         return;
     isInit = true;      // ### not atomic
-#ifdef Q_OS_UNIX
-    if (qgetenv("QT_ACCESSIBILITY") != "1")
-        return;
-#endif
+
 #ifndef QT_NO_LIBRARY
     const QStringList l = bridgeloader()->keys();
     for (int i = 0; i < l.count(); ++i) {