[oe] making possible to bake meta-toolchain-qt5 without opengl

[Ivan Sergio Borgonovo]

I'm going to send my first patch to oe.
It will be mostly a request for comments.

I think I could "skip" less packages in RDEPENDS_${PN} but probably some 
dependencies in qt5 should be improved.

patch hopefully coming to the list soon... If I make no further mistakes 
with git.

thanks

-- 
Ivan Sergio Borgonovo
http://www.webthatworks.it