Add EglDisplay case to nativeResourceForContext on eglfs

This is needed to make it possible to use the same interface for
retrieving the EGLDisplay on Windows and EGLFS, thus get rid of
cluttering ifdefs.

Change-Id: I37b848b1017eacbf8a29627cd157b74e22e5f40c
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/platformsupport/eglconvenience/qeglplatformintegration.cpp

@@ -291,6 +291,10 @@ void *QEGLPlatformIntegration::nativeResourceForContext(const QByteArray &resour
         if (context->handle())
             result = static_cast<QEGLPlatformContext *>(context->handle())->eglConfig();
         break;
+    case EglDisplay:
+        if (context->handle())
+            result = static_cast<QEGLPlatformContext *>(context->handle())->eglDisplay();
+        break;
     default:
         break;
     }