dump_desc() can trigger "write_str_to_file(): Bug: We're writing a text string that already contains a CR" on Windows

dump_desc() calls write_str_to_file() with bin==0, which on Windows causes an LD_BUG warn if the thing you're writing has a \r in it.

In this case, we're writing the thing because it came from the network and we couldn't parse it. So we could totally give a Windows relay or client a thing that they can't parse which has a \r in it, causing this LD_BUG log to trigger.

Noticed by looking at #11233 (moved). Unclear if it's the same location as was triggered in that bug though.