CONFIG_M68KFPU_EMU is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

Math emulation support

configname: CONFIG_M68KFPU_EMU

Linux Kernel Configuration
└─>Math emulation support
In linux kernel since version 2.6.12  
At some point in the future, this will cause floating-point math
instructions to be emulated by the kernel on machines that lack a
floating-point math coprocessor. Thrill-seekers and chronically
sleep-deprived psychotic hacker types can say Y now, everyone else
should probably wait a while.