New option -signal_handling

xorriso/opts_d_h.c

@@ -1871,6 +1871,8 @@ int Xorriso_option_help(struct XorrisO *xorriso, int flag)
 "              exit_value may be 0 or 32 to 63.",
 "  -report_about severity   Set the threshhold for events to be reported.",
 "              Use -abort_on severities or: HINT, NOTE, UPDATE, DEBUG, ALL",
+"  -signal_handling \"on\"|\"off\"|\"sig_dfl\"|\"sig_ign\"",
+"              Handling of signals. Default \"on\" uses libburn handler.",
 "  -error_behavior \"image_loading\"|\"file_extraction\" behavior",
 "              Behavior \"best_effort\" is most endurant but may produce",
 "              results which are correct only on the first glimpse.",