CONFIG_CSRC_R4K_LIB is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_CSRC_R4K_LIB (not configurable)

modulename: csrc-r4k.ko

configname: CONFIG_CSRC_R4K_LIB

Linux/MIPS Kernel Configuration
└─>CSRC_R4K_LIB
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
source code:
arch/mips/kernel/csrc-r4k.c