compositor: Do not access members after deleting an instance

Change-Id: I4edb73d0b4476492db8e6993e06cd6402cd55180
Reviewed-by: Giulio Camuffo <giulio.camuffo@jollamobile.com>
Explicitly define the interface versions

Currently a global is bound with the version the interface has in the xml
file. This is a problem for apps that explicitly link to libwayland-client
because they may link to a newer libwayland, so the version of some interface
may be higher than the one that it is actually implemented.

Change-Id: Id0dbe6c0f1e05fe91954b9d8d9472d42d2053cdc
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Fix build with desktop OpenGL

Change-Id: I6a21f447f31e9eeeafed81275c33b0c2c79e1c8a
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>