systray_darwin.m: Compare Mac OS min version with value instead of macro

[teddywing]

I was getting this error building on Mac OS X 10.12:

$ pwd
<$GOPATH>/src/github.com/getlantern/systray/example
$ go run .
# github.com/getlantern/systray
systray_darwin.m:132:22: error: use of undeclared identifier 'NSControlStateValueOn'
systray_darwin.m:134:22: error: use of undeclared identifier 'NSControlStateValueOff'

The NSControlStateValueOn and NSControlStateValueOff were not
defined because Mac OS versions prior to 10.14 don't define
__MAC_10_14.

From /usr/include/Availability.h:

It is also possible to use the _VERSION_MIN_REQUIRED in source code to make one
source base that can be compiled to target a range of OS versions. It is best
to not use the MAC and _IPHONE* macros for comparisons, but rather their values.
That is because you might get compiled on an old OS that does not define a later
OS version macro, and in the C preprocessor undefined values evaluate to zero
in expresssions, which could cause the #if expression to evaluate in an unexpected
way.

#ifdef __MAC_OS_X_VERSION_MIN_REQUIRED
    // code only compiled when targeting Mac OS X and not iPhone
    // note use of 1050 instead of __MAC_10_5
    #if __MAC_OS_X_VERSION_MIN_REQUIRED < 1050
        // code in here might run on pre-Leopard OS
    #else
        // code here can assume Leopard or later
    #endif
#endif

See #75, #92.

[teddywing]

Thanks!

[antwal]

not working very well, I'm checking if it's my mistake in the code since I get a link error

signal: segmentation fault

checking SDK API diff , AppKit Diff 10.12 to 10.13+