Mapbox GL should disable GLES 3 on embedded

Else this error happens on build:

error: conflicting declaration of C function 'void glShaderSource(GLuint, GLsizei, const GLchar*, const GLint)'

apparently it is trying to include its own gl.h, which conflicts with the one in /usr/include.

It seems that this is the same problem here for wayland:

http://code.qt.io/cgit/qt/qtwayland.git/commit/?id=d5e7965a87d81e2d7157c785403b0aba681de62a

and may be related to this khronos bug ? I'm not sure: https://www.khronos.org/bugzilla/show_bug.cgi?id=761