change defined(debug) to isDefined(conf, "nimDebug") in msgs.quit for debugging nim

[timotheecour]

links

pr_system_module_needs_show_stacktrace_bak1
pr_system_module_needs_show_stacktrace (deleted ; was nim-lang#10575)
nim-lang#10575 (comment)

makes it configurable at RT instead of fixed at CT

in here

proc quit(conf: ConfigRef; msg: TMsgKind) {.gcsafe.} =
  if defined(debug) or msg == errInternal or conf.hasHint(hintStackTrace):
    {.gcsafe.}:
      if stackTraceAvailable() and isNil(conf.writelnHook):
        writeStackTrace()
      else:
        styledMsgWriteln(fgRed, "No stack traceback available\n" &
            "To create a stacktrace, rerun compilation with ./koch temp " &
            conf.command & " <file>")
  quit 1