This is about "unable to create font set" bug. I ran into this problem when trying to compile XBoard from master-20110507 on Puppy Wary-511. The bug went away by itself after the (tiny) system language pack was installed, I was since unable to reproduce it neither without that package nor on a fresh save file (= fresh linux installation). So, this probably happend due to some remnants of previous XBoard versions. Now XBoard runs and only shows this warning in the terminal: Missing charsets in String to FontSet conversion.
It's still impossible to use localized version, though. For example, the Russian word Файл appears this way: Файл