In message 20060411020747.37569.qmail@web508.biz.mail.mud.yahoo.com you wrote:

I then tried again from the problem machine and U-boot built fine. Since then, the make problem has mysteriously gone away, even in other build areas.

Did you really run a "make mrproper" in the U-Boot tree, or otherwise made sure you really started with a clean tree without old pre-built (and eventually bad) build results?

Note that you must run the "make mrproper" using the old (working) make - chances are that the clean step will also fail, leaving unwanted files around.

Best regards,

Wolfgang Denk