Handle %7c with small letters.
Make sure that the output parameter's content is not
affected by decoding.

Change-Id: Ie3faad2461815497c0edfb04a589fc57aeb7d66b
Reviewed-on: https://gerrit.libreoffice.org/70873
Tested-by: Jenkins
Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>