egl: fix software flag in _eglAddDevice call on DRM

On the EGL DRM platform, call _eglAddDevice with the software flag
set if GBM has loaded a software driver. This allows _eglAddDevice
to make the difference between llvmpipe and kmsro.

This is important on split render/display SoCs: we don't want to
advertise EGL_MESA_device_software on these systems.

Completely drop disp->Options.ForceSoftware, because GBM is
responsible for choosing software rendering and doesn't take this
hint into account.

Signed-off-by: Simon Ser <contact@emersion.fr>
Fixes: 5743a36b2b ("egl: Don't add hardware device if there is no render node v2.")
References: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4178
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9697>

src/egl/drivers/dri2/platform_drm.c

@@ -718,7 +718,7 @@ dri2_initialize_drm(_EGLDisplay *disp)
       goto cleanup;
    }
 
-   dev = _eglAddDevice(dri2_dpy->fd, disp->Options.ForceSoftware);
+   dev = _eglAddDevice(dri2_dpy->fd, dri2_dpy->gbm_dri->software);
    if (!dev) {
       err = "DRI2: failed to find EGLDevice";
       goto cleanup;

src/gbm/backends/dri/gbm_dri.c

@@ -486,10 +486,13 @@ dri_screen_create_sw(struct gbm_dri_device *dri)
       return -errno;
 
    ret = dri_screen_create_dri2(dri, driver_name);
-   if (ret == 0)
+   if (ret != 0)
+      ret = dri_screen_create_swrast(dri);
+   if (ret != 0)
       return ret;
 
-   return dri_screen_create_swrast(dri);
+   dri->software = true;
+   return 0;
 }
 
 static const struct gbm_dri_visual gbm_dri_visuals_table[] = {

src/gbm/backends/dri/gbm_driint.h

@@ -63,6 +63,7 @@ struct gbm_dri_device {
 
    void *driver;
    char *driver_name; /* Name of the DRI module, without the _dri suffix */
+   bool software; /* A software driver was loaded */
 
    __DRIscreen *screen;
    __DRIcontext *context;