[PATCH] configure: resolve real path to bash

[David Bremner]

Đoàn Trần Công Danh <congdanhqx at gmail.com> writes:

> The old code somehow resolves to `bin/sh' on Arch Linux/Void Linux
> auto build systems.
>

I'm not sure if this is better or worse than

    https://nmbug.notmuchmail.org/nmweb/show/20190117021132.28327-1-david%40tethera.net

I welcome input on this.

One issue is that readlink(1) is not in POSIX, so we can expect some
portability pains.

d