We don't build curl for iOS. (Don't remember why exactly, but anyway,
this persona thing is surely a feature relevant for desktop platforms
only, and certainly not a good reason to start building curl.)

Change-Id: Ia2acebe77a0acb9dbf5858e6524c444e772ac8c8
Reviewed-on: https://gerrit.libreoffice.org/61520
Tested-by: Jenkins
Reviewed-by: Tor Lillqvist <tml@collabora.com>