Avoids the new Wunterminated-string-literal when compiled with gcc 15.1.
It would be preferable to just disable this warning, but Clang
-Wunknown-warning-option kicks in even when disabling warnings so this
becomes fiddly to apply.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>