apertium crashes with bad_alloc

I've attached an excerpt of about 25 lines that causes apertium to be busy for a long time and eventually crash with a bad_alloc exception.

Troublesome excerpt: [apertium-bug-ca-es-bad-alloc.txt](https://github.com/apertium/apertium/files/4824939/apertium-bug-ca-es-bad-alloc.txt)

I'm feeding apertium (with the cat-spa model) internet archive text to translate it line by line. The data itself is pretty noisy, which might give me garbage output, but that I'm fine with.

My "pipeline":
```
cat apertium-bug-ca-es-bad-alloc.txt \
| apertium-destxt -i \
| apertium -f none -u cat-spa \
| apertium-retxt \
> out.txt
```

Apertium is compiled from the source in this repository, at 267d7555af270261916d89980250cf3cd7df8f0c.