ui: Allow specifying 'rendernode' display option for egl-headless

As libvirt can't predict which rendernode QEMU would pick, it
won't adjust the permissions on the device, hence QEMU getting
"Permission denied" when opening the DRI device. Therefore, enable
'rendernode' option for egl-headless display type.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1648236Signed-off-by: NErik Skultety <eskultet@redhat.com>
Message-id: 27f4617f19aa1072114f10f1aa9dd199735ef982.1542362949.git.eskultet@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

ui/egl-headless.c

@@ -176,7 +176,7 @@ static void egl_headless_init(DisplayState *ds, DisplayOptions *opts)
     egl_dpy *edpy;
     int idx;
 
-    if (egl_rendernode_init(NULL, mode) < 0) {
+    if (egl_rendernode_init(opts->u.egl_headless.rendernode, mode) < 0) {
         error_report("egl: render node init failed");
         exit(1);
     }