package/libevas: switch dependency from mesa3d to _HAS_LIBGL

We now have a virtual package that represents availability of
full OpenGL.

This should be the end of this dependency hell epic, now. :-)

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>