trivial: Fix warning when compiling without libcurl
trivial: Fix warning when compiling without libcurl

hughsie/fwupd,fwupd/fwupd,hughsie/fwupd,fwupd/fwupd,hughsie/fwupd,fwupd/fwupd,fwupd/fwupd,hughsie/fwupd