Targeted to macOS (where `~/Downloads` is considered a sensitive location that the system protects behind a prompt even from non-sandboxed apps)
Signed-off-by: Kenneth Chew <79120643+kthchew@users.noreply.github.com>
Two new build options are added:
`MAC_SPARKLE_PUB_KEY`: the public key used to verify the signatures of the appcast
`MAC_SPARKLE_APPCAST_URL`: the URL where the `appcast.xml` is located
If the updater should be disabled on macOS, set either of these to an empty string.
