This allows compiling Objective-C files.
The temporary directory is needed because clang would try to write to `/dev/null.d`, which would obviously fail.
The new User Notifications Framework is only available on macOS 10.14 and above, while the old NSUserNotification API is deprecated in macOS 11 (Big Sur) and will probably be removed in the future.
This commit compiles a simple test program to see if the Framework is available and then uses either the new or the old API.
When piping the output of `setup.py` to another program, that program cannot usually deal with escape sequences well. To fix this, output the compilation progress on new lines instead of overwriting the current line.
Disabling Link Time Optimization is useful for Nix on Darwin because LTO is broken there and has been for a long time, see https://github.com/NixOS/nixpkgs/pull/19312.
This is currently worked around in the Nix package with a patch that removes the lines that add -flto to the compiler flags.
The current notifications framework has been deprecated in Big Sur. The new
framework only allows notifications from signed and notarized applications,
so people using kitty from HomeBrew/source are out of luck. And
notifications can only be displayed once the user grants permission. A
completely brain-dead design. Complain to Apple.
This required the kitty package to be moved from Frameworks to
Resources, because Apple cant codesign .pyc files and its notarization
requires everything in Frameworks to be signed. Hopefully that does not
break anything. Also removed the kitty-deref-symlink since it is not
needed anyway and was only present for backwards compatibility.
Fixes#2040
png2icns is used when building kitty with nix because iconutil seems to be closed-source.
libicns also has an iconutil clone called icnsutil in the source tree but the last release is from 2012, which does not include this utility yet.
According to the text just above https://docs.python.org/3/library/exceptions.html#EnvironmentError, `EnvironmentError` has been an alias of `OSError` since Python 3.3. Replacing it makes the code more consistent since `OSError` is used in other places in the code too.
