This script currently downloads the .zip file from the web into a local
file with no file extension. This can cause issues for 7-zip when
unarchiving. This patch fixes this.
As a drive-by, we improve the names of some variables.
Pick-to: 6.11 6.8
Change-Id: Icb1b24646b54d75d825764d30a268fa6e55d0183
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>