This prevents updates from failing if multiple instances of the
script are running in parallel. This fixes #7492.

Signed-off-by: Martin Konrad <info@martin-konrad.net>

* replace shell based urlencoder with an awk variant
* fix write_log function/syslog output in case of an error
* protect answer string with double quotes in update_route53
* remove bogus set/IFS options in update_route53
* clean-up update_route53 a little bit

This patchset finally fix #6977

Many thanks to @mark0n & @a-bali for testing & debugging

Signed-off-by: Dirk Brenken <dev@brenken.org>

Based on a sh-only route53 update script by Yuval Adam
https://github.com/yuvadm/route53-ddns/blob/master/route53.sh

Signed-off-by: Max Berger <max@berger.name>