New bootspec "gpt_disk_guid=", new -as mkisofs option --gpt_disk_guid, new -report_system_area mode "make_guid"

xorriso/xorriso_private.h

@@ -497,6 +497,10 @@ struct XorrisO { /* the global context of xorriso */
  /* If 1: Apply isohybrid gestures to non-isohybrid situations */
  int part_like_isohybrid;
 
+ /* See libisoburn.h isoburn_igopt_set_gpt_guid() */
+ uint8_t gpt_guid[16];
+ int gpt_guid_mode;
+
  /* Eventual name of the non-ISO aspect of the image. E.g. SUN ASCII label.
  */
  char ascii_disc_label[Xorriso_disc_label_sizE];