Fix a bug that prevented the creation of EGL shared contexts.

    int i=0, index=0;

    egl_connection_t* cnx = validate_display_config(dpy, config, dp, i, index);

    if (cnx) {

        if (share_list != EGL_NO_CONTEXT) {

            egl_context_t* const c = get_context(share_list);

            share_list = c->context;

        }

        EGLContext context = cnx->egl.eglCreateContext(

                dp->disp[i].dpy, dp->disp[i].config[index],

                share_list, attrib_list);