Make md5sum/sha1sum -b flag be "brief" output (just the hash).

(It's not like systems implementing -b binary and -t text still matter.)
Minor tweaks to code style section.
Replace large parenthetical in bloatcheck with a function.
Isaac Dunham pointed out that busybox diff only implements unified diffs, and sent a patch to convert bloatcheck to use that. I tweaked it a bit.
Isaac Dunham also reported that some diff implementations can't handle nonseekable input, so write to a temporary file instead of <(command).

Use trap EXIT to make sure the temporary files get deleted.
Add host by Rich Felker.