util/readline: add a space to fix errors by checkpatch tool

util/readline: add a space to fix errors reported by checkpatch.pl tool
"ERROR: space required before the open parenthesis"
"ERROR: space required after that ..."
within "util/redline.c" file

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20190401024406.10819-2-jbi.octave@gmail.com
Message-Id: <20190401024406.10819-2-jbi.octave@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>