CONFIG_MAC is not available for the selected architecture x86.
Result is shown for architecture m68k

Macintosh support

configname: CONFIG_MAC

Linux/68k Kernel Configuration
└─>Platform dependent setup
└─>Macintosh support
In linux kernel since version 2.6.12 )
This option enables support for the Apple Macintosh series of
computers (yes, there is experimental support now, at least for part
of the series).

Say N unless you're willing to code the remaining necessary support.
;)