That is strange; I bootstrap regularly with `--enable-debug` and have not seen an arithmetic overflow during bootstrap (at least, not for a long time).
It would probably be best to carry on a conversation on a formal bug report; did you file one at the url it listed?
http://pastebin.com/bifK665u
I set --prefix=/usr --enable-debug
No dice. I also tried to build from source in a VM on that same machine. 32-bit Ubuntu 14.04.2 (3GB of RAM), latest stable toolchain. Again, didn't compile. Core dump.