[PATCH] Rebuild benchmark sources when Makefile is updated

[Roland McGrath]

I may be missing some context because I didn't find time to review your
original bench/ additions and they went in without my involvement.

Why is any of this stuff in Rules at all?  It appears to be relevant only
to bench/Makefile and so it should be there.  Is there some intent to
support the 'bench' variable in other subdir makefiles?


Thanks,
Roland