CONFIG_SCHED_MC is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Multi-core scheduler support

configname: CONFIG_SCHED_MC

Linux Kernel Configuration
└─>Memory management options
└─>Multi-core scheduler support
In linux kernel since version 2.6.17 (release Date: 2006-06-17)  
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.

depends
CONFIG_SMP

is selected by
CONFIG_SCHED_MC_PRIO