Scheme test driver should use ‘write’

[Ludovic Courtès]

Hi!

I just noticed that our fancy ‘build-aux/test-driver.scm’ uses ‘display’
instead of ‘write’ to write test values.

So for instance, in tests/gremlin.log, we have:

--8<---------------cut here---------------start------------->8---
test-name: expand-origin

[...]

expected-value: (OOO/../lib OOO ../OOO/bar/OOO/baz ORIGIN/foo)
--8<---------------cut here---------------end--------------->8---

… where we’d instead prefer to see:

--8<---------------cut here---------------start------------->8---
expected-value: ("OOO/../lib" "OOO" "../OOO/bar/OOO/baz" "ORIGIN/foo")
--8<---------------cut here---------------end--------------->8---

I figured I’d let you look into it.  :-)
No rush though.

Ludo’.