I'm not sure you will still read this or care, but I ran into a similar issue with configure in a different build I ran (unrelated to LibreELEC), but it turns out that the leading dash (or minus) in the host triplet passed to config.sub was the issue.
Check to make sure that the host triplet (passed to configure using --host=... is the proper one ... and it shouldn't really start with a dash).
Now I don't know how it ended up there for you, in my case it was a mistake on my part when I manipulated a script using another script.
The problem is likely caused because the leading dash ends up confusing some command being called during the run of one of the configure (and related) scripts. Likely it's being deemed a command line switch ...
Hope this helps someone down the road.