macOS 10.14 deprecated NSOnState/NSOffState in favour of
NSControlStateValueOn/NSControlStateValueOff. Use the new constants,
and #define them to the old ones when compiling against a pre-10.13 SDK.
Also [NSGraphicsContext graphicsPort] is now deprecated, use
[NSGraphicsContext CGContext] when available.

Signed-off-by: Brendan Shanks <brendan@bslabs.net>
Message-id: 20190201071225.20576-1-brendan@bslabs.net
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>