Infinite loop when appending filename to pages that are too narrow

[slobo]

Thanks for the great library. We had our scanner spit out a very narrow page, and when we tried to merge that documents with --footer the merge got stuck. The last message it prints out before consuming 100% CPU is

Page filename footer needs truncating to fit available space

Looking through the source, seems that truncateIfRequired maybe doesn't exit one of the while loops in these situations.

https://github.com/torakiki/sejda/blob/master/sejda-sambox/src/main/java/org/sejda/impl/sambox/component/FilenameFooterWriter.java#L94

I'll note that we are using this with sejda-console 3.2.85, feel free to ignore this report if you've fixed this in the latest pro release.

Cheers