Bug#849517: The valgrind diagnostic is a false positive

[Florian Weimer]

* Reuben Thomas:

> ​A workaround is to build bash with --without-bash-malloc (but I presume
> there's a good reason not to do that?).​

FWIW, Fedora and Red Hat Enterprise Linux compile bash this way, so it
can't be *that* bad.