CONFIG_CPU_LOONGSON1C is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Loongson 1C

configname: CONFIG_CPU_LOONGSON1C

CPU type
└─>Loongson 1C
In linux kernel since version 4.1 (release Date: 2015-06-21)  
The Loongson 1C is a 32-bit SoC, which implements the MIPS32
release 2 instruction set.