package/mesa3d: with a DRI driver, is a full OpenGL provider

Make mesa3d a provider for full OpenGL, as soon as a DRI driver is enabled.

Full OpenGL is only possible when:
  - a DRI driver is enabled,
  - and X.Org is enabled

Since DRI driver in fact depend on X.Org being enabled in the first place,
we can safely declare mesa3d as a full openGL provider as soon as at least
one DRI driver is enabled.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Bernd Kuhls <berndkuhls@hotmail.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>