Alastair Hughes authored Aug 12, 2017 and Allan McRae committed Sep 14, 2017

Not all sed implementations on linux accept the --follow-symlinks
argument, so let the user configure the arguments passed to sed if
required.

Signed-off-by: Alastair Hughes <hobbitalastair@gmail.com>

[Allan: fixed configure summary output]
Signed-off-by: Allan McRae <allan@archlinux.org>