runqemu: force software x11 renderer for SDL when GL is not in use
If libsdl is configured with opengl enabled, it will try to use GL
renderers to open a window even if qemu doesn't use virgl. Setting
the environment variable forces a software X11 renderer, which is the
same one used when libsdl has opengl switched off. This avoids
needlessly loading the GL libraries and drivers from the host.
Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
