Remove #ifndef QT_NO_ACCESSIBILITY around qaccessible.{h,cpp}

Remove #ifndef QT_NO_ACCESSIBILITY around qaccessible.{h,cpp}

Jens has an use-case for using accessibility from styles.

By making the enums always available regardless of QT_NO_ACCESSIBILITY,
it makes the style code less littered with ifndefs.

It should (ahem) also solve the problem where Qt Desktop components
does not compile if QT_NO_ACCESSIBILITY is not defined.
This happens on some linux distros, since atspi-2-dev is not installed
by default, which again causes grief for those affected.

Change-Id: I15d65df8c752a0c4af37cc7b4d908a757cb6a9c4
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>